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Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > Class Template Reference

Detailed Description

template<typename _Scalar, int _Rows, int _Cols, int _Options, int _MaxRows, int _MaxCols>
class Eigen::Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols >

The matrix class, also used for vectors and row-vectors.

The Matrix class is the work-horse for all dense (note) matrices and vectors within Eigen. Vectors are matrices with one column, and row-vectors are matrices with one row.

The Matrix class encompasses both fixed-size and dynamic-size objects (note).

The first three template parameters are required:

Template Parameters
_ScalarNumeric type, e.g. float, double, int or std::complex<float>. User defined sclar types are supported as well (see here).
_RowsNumber of rows, or Dynamic
_ColsNumber of columns, or Dynamic

The remaining template parameters are optional – in most cases you don't have to worry about them.

Template Parameters
_OptionsA combination of either RowMajor or ColMajor, and of either AutoAlign or DontAlign. The former controls storage order, and defaults to column-major. The latter controls alignment, which is required for vectorization. It defaults to aligning matrices except for fixed sizes that aren't a multiple of the packet size.
_MaxRowsMaximum number of rows. Defaults to _Rows (note).
_MaxColsMaximum number of columns. Defaults to _Cols (note).

Eigen provides a number of typedefs covering the usual cases. Here are some examples:

  • Matrix2d is a 2x2 square matrix of doubles (Matrix<double, 2, 2>)
  • Vector4f is a vector of 4 floats (Matrix<float, 4, 1>)
  • RowVector3i is a row-vector of 3 ints (Matrix<int, 1, 3>)
  • MatrixXf is a dynamic-size matrix of floats (Matrix<float, Dynamic, Dynamic>)
  • VectorXf is a dynamic-size vector of floats (Matrix<float, Dynamic, 1>)
  • Matrix2Xf is a partially fixed-size (dynamic-size) matrix of floats (Matrix<float, 2, Dynamic>)
  • MatrixX3d is a partially dynamic-size (fixed-size) matrix of double (Matrix<double, Dynamic, 3>)

See this page for a complete list of predefined Matrix and Vector typedefs.

You can access elements of vectors and matrices using normal subscripting:

v[0] = 0.1;
v[1] = 0.2;
v(0) = 0.3;
v(1) = 0.4;
Eigen::MatrixXi m(10, 10);
m(0, 1) = 1;
m(0, 2) = 2;
m(0, 3) = 3;

This class can be extended with the help of the plugin mechanism described on the page Customizing/Extending Eigen by defining the preprocessor symbol EIGEN_MATRIX_PLUGIN.

Some notes:

Dense versus sparse:

This Matrix class handles dense, not sparse matrices and vectors. For sparse matrices and vectors, see the Sparse module.

Dense matrices and vectors are plain usual arrays of coefficients. All the coefficients are stored, in an ordinary contiguous array. This is unlike Sparse matrices and vectors where the coefficients are stored as a list of nonzero coefficients.

Fixed-size versus dynamic-size:

Fixed-size means that the numbers of rows and columns are known are compile-time. In this case, Eigen allocates the array of coefficients as a fixed-size array, as a class member. This makes sense for very small matrices, typically up to 4x4, sometimes up to 16x16. Larger matrices should be declared as dynamic-size even if one happens to know their size at compile-time.

Dynamic-size means that the numbers of rows or columns are not necessarily known at compile-time. In this case they are runtime variables, and the array of coefficients is allocated dynamically on the heap.

Note that dense matrices, be they Fixed-size or Dynamic-size, do not expand dynamically in the sense of a std::map. If you want this behavior, see the Sparse module.

_MaxRows and _MaxCols:
In most cases, one just leaves these parameters to the default values. These parameters mean the maximum size of rows and columns that the matrix may have. They are useful in cases when the exact numbers of rows and columns are not known are compile-time, but it is known at compile-time that they cannot exceed a certain value. This happens when taking dynamic-size blocks inside fixed-size matrices: in this case _MaxRows and _MaxCols are the dimensions of the original matrix, while _Rows and _Cols are Dynamic.
See Also
MatrixBase for the majority of the API methods for matrices, The class hierarchy, Storage orders
+ Inheritance diagram for Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols >:

Public Types

typedef PlainObjectBase< MatrixBase
 Base class typedef.

Public Member Functions

ArrayWrapper< Matrix< _Scalar,
_Rows, _Cols, _Options,
_MaxRows, _MaxCols > > 
array ()
const CwiseBinaryOp
< CustomBinaryOp, const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, const OtherDerived > 
binaryExpr (const Eigen::MatrixBase< OtherDerived > &other, const CustomBinaryOp &func=CustomBinaryOp()) const
Block< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols > > 
block (Index startRow, Index startCol, Index blockRows, Index blockCols)
const Block< const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols > > 
block (Index startRow, Index startCol, Index blockRows, Index blockCols) const
Block< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols >, BlockRows,
BlockCols > 
block (Index startRow, Index startCol)
const Block< const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, BlockRows, BlockCols > 
block (Index startRow, Index startCol) const
Block< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols >, BlockRows,
BlockCols > 
block (Index startRow, Index startCol, Index blockRows, Index blockCols)
const Block< const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, BlockRows, BlockCols > 
block (Index startRow, Index startCol, Index blockRows, Index blockCols) const
Block< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols > > 
bottomLeftCorner (Index cRows, Index cCols)
const Block< const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols > > 
bottomLeftCorner (Index cRows, Index cCols) const
Block< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols >, CRows, CCols > 
bottomLeftCorner ()
const Block< const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, CRows, CCols > 
bottomLeftCorner () const
Block< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols >, CRows, CCols > 
bottomLeftCorner (Index cRows, Index cCols)
const Block< const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, CRows, CCols > 
bottomLeftCorner (Index cRows, Index cCols) const
Block< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols > > 
bottomRightCorner (Index cRows, Index cCols)
const Block< const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols > > 
bottomRightCorner (Index cRows, Index cCols) const
Block< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols >, CRows, CCols > 
bottomRightCorner ()
const Block< const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, CRows, CCols > 
bottomRightCorner () const
Block< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols >, CRows, CCols > 
bottomRightCorner (Index cRows, Index cCols)
const Block< const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, CRows, CCols > 
bottomRightCorner (Index cRows, Index cCols) const
RowsBlockXpr bottomRows (Index n)
ConstRowsBlockXpr bottomRows (Index n) const
NRowsBlockXpr< N >::Type bottomRows ()
ConstNRowsBlockXpr< N >::Type bottomRows () const
internal::cast_return_type
< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols >, const CwiseUnaryOp
< internal::scalar_cast_op
< typename internal::traits
< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols > >::Scalar, NewType >
, const Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols > > >::type 
cast () const
ColXpr col (Index i)
ConstColXpr col (Index i) const
ConjugateReturnType conjugate () const
void conservativeResize (Index nbRows, Index nbCols)
void conservativeResize (Index nbRows, NoChange_t)
void conservativeResize (NoChange_t, Index nbCols)
void conservativeResize (Index size)
void conservativeResizeLike (const DenseBase< OtherDerived > &other)
const CwiseUnaryOp
< internal::scalar_abs_op
< Scalar >, const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols > > 
cwiseAbs () const
const CwiseUnaryOp
< internal::scalar_abs2_op
< Scalar >, const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols > > 
cwiseAbs2 () const
const CwiseBinaryOp
< std::equal_to< Scalar >
, const Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols >, const OtherDerived > 
cwiseEqual (const Eigen::MatrixBase< OtherDerived > &other) const
const CwiseUnaryOp
< std::binder1st
< std::equal_to< Scalar >
>, const Matrix< _Scalar,
_Rows, _Cols, _Options,
_MaxRows, _MaxCols > > 
cwiseEqual (const Scalar &s) const
const CwiseUnaryOp
< internal::scalar_inverse_op
< Scalar >, const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols > > 
cwiseInverse () const
const CwiseBinaryOp
< internal::scalar_max_op
< Scalar >, const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, const OtherDerived > 
cwiseMax (const Eigen::MatrixBase< OtherDerived > &other) const
const CwiseBinaryOp
< internal::scalar_max_op
< Scalar >, const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, const ConstantReturnType > 
cwiseMax (const Scalar &other) const
const CwiseBinaryOp
< internal::scalar_min_op
< Scalar >, const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, const OtherDerived > 
cwiseMin (const Eigen::MatrixBase< OtherDerived > &other) const
const CwiseBinaryOp
< internal::scalar_min_op
< Scalar >, const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, const ConstantReturnType > 
cwiseMin (const Scalar &other) const
const CwiseBinaryOp
< std::not_equal_to< Scalar >
, const Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols >, const OtherDerived > 
cwiseNotEqual (const Eigen::MatrixBase< OtherDerived > &other) const
const CwiseBinaryOp
< internal::scalar_product_op
< typename Matrix< _Scalar,
_Rows, _Cols, _Options,
_MaxRows, _MaxCols >::Scalar,
typename OtherDerived::Scalar >
, const Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols >, const OtherDerived > 
cwiseProduct (const Eigen::MatrixBase< OtherDerived > &other) const
const CwiseBinaryOp
< internal::scalar_quotient_op
< Scalar >, const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, const OtherDerived > 
cwiseQuotient (const Eigen::MatrixBase< OtherDerived > &other) const
const CwiseUnaryOp
< internal::scalar_sqrt_op
< Scalar >, const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols > > 
cwiseSqrt () const
const Scalar * data () const
Scalar * data ()
Index diagonalSize () const
EvalReturnType eval () const
SegmentReturnType head (Index vecSize)
ConstSegmentReturnType head (Index vecSize) const
FixedSegmentReturnType< Size >
::Type 
head ()
ConstFixedSegmentReturnType
< Size >::Type 
head () const
const ImagReturnType imag () const
NonConstImagReturnType imag ()
Index innerSize () const
Matrix< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols > & 
lazyAssign (const DenseBase< OtherDerived > &other)
ColsBlockXpr leftCols (Index n)
ConstColsBlockXpr leftCols (Index n) const
NColsBlockXpr< N >::Type leftCols ()
ConstNColsBlockXpr< N >::Type leftCols () const
 Matrix ()
 Default constructor.
 Matrix (Index dim)
 Constructs a vector or row-vector with given dimension. This is only for vectors (either row-vectors or column-vectors), i.e. matrices which are known at compile-time to have either one row or one column.
 Matrix (Index rows, Index cols)
 Constructs an uninitialized matrix with rows rows and cols columns.
 Matrix (const Scalar &x, const Scalar &y)
 Constructs an initialized 2D vector with given coefficients.
 Matrix (const Scalar &x, const Scalar &y, const Scalar &z)
 Constructs an initialized 3D vector with given coefficients.
 Matrix (const Scalar &x, const Scalar &y, const Scalar &z, const Scalar &w)
 Constructs an initialized 4D vector with given coefficients.
template<typename OtherDerived >
 Matrix (const MatrixBase< OtherDerived > &other)
 Constructor copying the value of the expression other.
 Matrix (const Matrix &other)
 Copy constructor.
template<typename OtherDerived >
 Matrix (const ReturnByValue< OtherDerived > &other)
 Copy constructor with in-place evaluation.
template<typename OtherDerived >
 Matrix (const EigenBase< OtherDerived > &other)
 Copy constructor for generic expressions.
template<typename OtherDerived >
 Matrix (const RotationBase< OtherDerived, ColsAtCompileTime > &r)
 Constructs a Dim x Dim rotation matrix from the rotation r.
ColsBlockXpr middleCols (Index startCol, Index numCols)
ConstColsBlockXpr middleCols (Index startCol, Index numCols) const
NColsBlockXpr< N >::Type middleCols (Index startCol)
ConstNColsBlockXpr< N >::Type middleCols (Index startCol) const
RowsBlockXpr middleRows (Index startRow, Index numRows)
ConstRowsBlockXpr middleRows (Index startRow, Index numRows) const
NRowsBlockXpr< N >::Type middleRows (Index startRow)
ConstNRowsBlockXpr< N >::Type middleRows (Index startRow) const
Index nonZeros () const
bool operator!= (const MatrixBase< OtherDerived > &other) const
const ScalarMultipleReturnType operator* (const Scalar &scalar) const
const CwiseUnaryOp
< internal::scalar_multiple2_op
< Scalar, std::complex< Scalar >
>, const Matrix< _Scalar,
_Rows, _Cols, _Options,
_MaxRows, _MaxCols > > 
operator* (const std::complex< Scalar > &scalar) const
const CwiseBinaryOp
< internal::scalar_sum_op
< Scalar >, const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, const OtherDerived > 
operator+ (const Eigen::MatrixBase< OtherDerived > &other) const
const CwiseBinaryOp
< internal::scalar_difference_op
< Scalar >, const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, const OtherDerived > 
operator- (const Eigen::MatrixBase< OtherDerived > &other) const
const CwiseUnaryOp
< internal::scalar_opposite_op
< typename internal::traits
< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols > >::Scalar >, const
Matrix< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols > > 
operator- () const
const CwiseUnaryOp
< internal::scalar_quotient1_op
< typename internal::traits
< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols > >::Scalar >, const
Matrix< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols > > 
operator/ (const Scalar &scalar) const
Matrixoperator= (const Matrix &other)
 Assigns matrices to each other.
template<typename OtherDerived >
Matrixoperator= (const EigenBase< OtherDerived > &other)
 Copies the generic expression other into *this.
template<typename OtherDerived >
Matrixoperator= (const RotationBase< OtherDerived, ColsAtCompileTime > &r)
 Set a Dim x Dim rotation matrix from the rotation r.
bool operator== (const MatrixBase< OtherDerived > &other) const
Index outerSize () const
RealReturnType real () const
NonConstRealReturnType real ()
void resize (Index nbRows, Index nbCols)
void resize (Index size)
void resize (NoChange_t, Index nbCols)
void resize (Index nbRows, NoChange_t)
void resizeLike (const EigenBase< OtherDerived > &_other)
ColsBlockXpr rightCols (Index n)
ConstColsBlockXpr rightCols (Index n) const
NColsBlockXpr< N >::Type rightCols ()
ConstNColsBlockXpr< N >::Type rightCols () const
RowXpr row (Index i)
ConstRowXpr row (Index i) const
SegmentReturnType segment (Index start, Index vecSize)
ConstSegmentReturnType segment (Index start, Index vecSize) const
FixedSegmentReturnType< Size >
::Type 
segment (Index start)
ConstFixedSegmentReturnType
< Size >::Type 
segment (Index start) const
void swap (const DenseBase< OtherDerived > &other, int=OtherDerived::ThisConstantIsPrivateInPlainObjectBase)
void swap (PlainObjectBase< OtherDerived > &other)
SegmentReturnType tail (Index vecSize)
ConstSegmentReturnType tail (Index vecSize) const
FixedSegmentReturnType< Size >
::Type 
tail ()
ConstFixedSegmentReturnType
< Size >::Type 
tail () const
Block< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols > > 
topLeftCorner (Index cRows, Index cCols)
const Block< const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols > > 
topLeftCorner (Index cRows, Index cCols) const
Block< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols >, CRows, CCols > 
topLeftCorner ()
const Block< const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, CRows, CCols > 
topLeftCorner () const
Block< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols >, CRows, CCols > 
topLeftCorner (Index cRows, Index cCols)
const Block< const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, CRows, CCols > 
topLeftCorner (Index cRows, Index cCols) const
Block< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols > > 
topRightCorner (Index cRows, Index cCols)
const Block< const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols > > 
topRightCorner (Index cRows, Index cCols) const
Block< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols >, CRows, CCols > 
topRightCorner ()
const Block< const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, CRows, CCols > 
topRightCorner () const
Block< Matrix< _Scalar, _Rows,
_Cols, _Options, _MaxRows,
_MaxCols >, CRows, CCols > 
topRightCorner (Index cRows, Index cCols)
const Block< const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols >
, CRows, CCols > 
topRightCorner (Index cRows, Index cCols) const
RowsBlockXpr topRows (Index n)
ConstRowsBlockXpr topRows (Index n) const
NRowsBlockXpr< N >::Type topRows ()
ConstNRowsBlockXpr< N >::Type topRows () const
const CwiseUnaryOp
< CustomUnaryOp, const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols > > 
unaryExpr (const CustomUnaryOp &func=CustomUnaryOp()) const
 Apply a unary operator coefficient-wise.
const CwiseUnaryView
< CustomViewOp, const Matrix
< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols > > 
unaryViewExpr (const CustomViewOp &func=CustomViewOp()) const
CoeffReturnType value () const

Static Public Member Functions

Map

These are convenience functions returning Map objects. The Map() static functions return unaligned Map objects, while the AlignedMap() functions return aligned Map objects and thus should be called only with 16-byte-aligned data pointers.

See Also
class Map
static ConstMapType Map (const Scalar *data)
static MapType Map (Scalar *data)
static ConstMapType Map (const Scalar *data, Index size)
static MapType Map (Scalar *data, Index size)
static ConstMapType Map (const Scalar *data, Index rows, Index cols)
static MapType Map (Scalar *data, Index rows, Index cols)
static StridedConstMapType
< Stride< Outer, Inner >
>::type 
Map (const Scalar *data, const Stride< Outer, Inner > &stride)
static StridedMapType< Stride
< Outer, Inner > >::type 
Map (Scalar *data, const Stride< Outer, Inner > &stride)
static StridedConstMapType
< Stride< Outer, Inner >
>::type 
Map (const Scalar *data, Index size, const Stride< Outer, Inner > &stride)
static StridedMapType< Stride
< Outer, Inner > >::type 
Map (Scalar *data, Index size, const Stride< Outer, Inner > &stride)
static StridedConstMapType
< Stride< Outer, Inner >
>::type 
Map (const Scalar *data, Index rows, Index cols, const Stride< Outer, Inner > &stride)
static StridedMapType< Stride
< Outer, Inner > >::type 
Map (Scalar *data, Index rows, Index cols, const Stride< Outer, Inner > &stride)
static ConstAlignedMapType MapAligned (const Scalar *data)
static AlignedMapType MapAligned (Scalar *data)
static ConstAlignedMapType MapAligned (const Scalar *data, Index size)
static AlignedMapType MapAligned (Scalar *data, Index size)
static ConstAlignedMapType MapAligned (const Scalar *data, Index rows, Index cols)
static AlignedMapType MapAligned (Scalar *data, Index rows, Index cols)
static
StridedConstAlignedMapType
< Stride< Outer, Inner >
>::type 
MapAligned (const Scalar *data, const Stride< Outer, Inner > &stride)
static StridedAlignedMapType
< Stride< Outer, Inner >
>::type 
MapAligned (Scalar *data, const Stride< Outer, Inner > &stride)
static
StridedConstAlignedMapType
< Stride< Outer, Inner >
>::type 
MapAligned (const Scalar *data, Index size, const Stride< Outer, Inner > &stride)
static StridedAlignedMapType
< Stride< Outer, Inner >
>::type 
MapAligned (Scalar *data, Index size, const Stride< Outer, Inner > &stride)
static
StridedConstAlignedMapType
< Stride< Outer, Inner >
>::type 
MapAligned (const Scalar *data, Index rows, Index cols, const Stride< Outer, Inner > &stride)
static StridedAlignedMapType
< Stride< Outer, Inner >
>::type 
MapAligned (Scalar *data, Index rows, Index cols, const Stride< Outer, Inner > &stride)

Protected Member Functions

Matrix< _Scalar, _Rows, _Cols,
_Options, _MaxRows, _MaxCols > & 
_set (const DenseBase< OtherDerived > &other)
 Copies the value of the expression other into *this with automatic resizing.

Member Typedef Documentation

Base class typedef.

See Also
PlainObjectBase

Constructor & Destructor Documentation

Matrix ( )
inline

Default constructor.

For fixed-size matrices, does nothing.

For dynamic-size matrices, creates an empty matrix of size 0. Does not allocate any array. Such a matrix is called a null matrix. This constructor is the unique way to create null matrices: resizing a matrix to 0 is not supported.

See Also
resize(Index,Index)
Matrix ( Index  dim)
inlineexplicit

Constructs a vector or row-vector with given dimension. This is only for vectors (either row-vectors or column-vectors), i.e. matrices which are known at compile-time to have either one row or one column.

Note that this is only useful for dynamic-size vectors. For fixed-size vectors, it is redundant to pass the dimension here, so it makes more sense to use the default constructor Matrix() instead.

Matrix ( Index  rows,
Index  cols 
)

Constructs an uninitialized matrix with rows rows and cols columns.

This is useful for dynamic-size matrices. For fixed-size matrices, it is redundant to pass these parameters, so one should use the default constructor Matrix() instead.

Matrix ( const EigenBase< OtherDerived > &  other)
inline

Copy constructor for generic expressions.

See Also
MatrixBase::operator=(const EigenBase<OtherDerived>&)
Matrix ( const RotationBase< OtherDerived, ColsAtCompileTime > &  r)
explicit

Constructs a Dim x Dim rotation matrix from the rotation r.

This is defined in the Geometry module.

#include <Eigen/Geometry>

References RotationBase< Derived, _Dim >::toRotationMatrix().

Member Function Documentation

Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > & _set ( const DenseBase< OtherDerived > &  other)
inlineprotectedinherited

Copies the value of the expression other into *this with automatic resizing.

*this might be resized to match the dimensions of other. If *this was a null matrix (not already initialized), it will be initialized.

Note that copying a row-vector into a vector (and conversely) is allowed. The resizing, if any, is then done in the appropriate way so that row-vectors remain row-vectors and vectors remain vectors.

See Also
operator=(const MatrixBase<OtherDerived>&), _set_noalias()
ArrayWrapper<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > array ( )
inlineinherited
Returns
an Array expression of this matrix
See Also
ArrayBase::matrix()
const CwiseBinaryOp<CustomBinaryOp, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , const OtherDerived> binaryExpr ( const Eigen::MatrixBase< OtherDerived > &  other,
const CustomBinaryOp &  func = CustomBinaryOp() 
) const
inlineinherited
Returns
an expression of a custom coefficient-wise operator func of *this and other

The template parameter CustomBinaryOp is the type of the functor of the custom operator (see class CwiseBinaryOp for an example)

Here is an example illustrating the use of custom functors:

#include <Eigen/Core>
#include <iostream>
using namespace Eigen;
using namespace std;
// define a custom template binary functor
template<typename Scalar> struct MakeComplexOp {
EIGEN_EMPTY_STRUCT_CTOR(MakeComplexOp)
typedef complex<Scalar> result_type;
complex<Scalar> operator()(const Scalar& a, const Scalar& b) const { return complex<Scalar>(a,b); }
};
int main(int, char**)
{
Matrix4d m1 = Matrix4d::Random(), m2 = Matrix4d::Random();
cout << m1.binaryExpr(m2, MakeComplexOp<double>()) << endl;
return 0;
}

Output:

   (0.68,0.271)  (0.823,-0.967) (-0.444,-0.687)   (-0.27,0.998)
 (-0.211,0.435) (-0.605,-0.514)  (0.108,-0.198) (0.0268,-0.563)
 (0.566,-0.717)  (-0.33,-0.726) (-0.0452,-0.74)  (0.904,0.0259)
  (0.597,0.214)   (0.536,0.608)  (0.258,-0.782)   (0.832,0.678)
See Also
class CwiseBinaryOp, operator+(), operator-(), cwiseProduct()
Block<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > block ( Index  startRow,
Index  startCol,
Index  blockRows,
Index  blockCols 
)
inlineinherited
Returns
a dynamic-size expression of a block in *this.
Parameters
startRowthe first row in the block
startColthe first column in the block
blockRowsthe number of rows in the block
blockColsthe number of columns in the block

Example:

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is m.block(1, 1, 2, 2):" << endl << m.block(1, 1, 2, 2) << endl;
m.block(1, 1, 2, 2).setZero();
cout << "Now the matrix m is:" << endl << m << endl;

Output:

Here is the matrix m:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is m.block(1, 1, 2, 2):
-6 1
-3 0
Now the matrix m is:
 7  9 -5 -3
-2  0  0  0
 6  0  0  9
 6  6  3  9
Note
Even though the returned expression has dynamic size, in the case when it is applied to a fixed-size matrix, it inherits a fixed maximal size, which means that evaluating it does not cause a dynamic memory allocation.
See Also
class Block, block(Index,Index)
const Block<const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > block ( Index  startRow,
Index  startCol,
Index  blockRows,
Index  blockCols 
) const
inlineinherited

This is the const version of block(Index,Index,Index,Index).

Block<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , BlockRows, BlockCols> block ( Index  startRow,
Index  startCol 
)
inlineinherited
Returns
a fixed-size expression of a block in *this.

The template parameters BlockRows and BlockCols are the number of rows and columns in the block.

Parameters
startRowthe first row in the block
startColthe first column in the block

Example:

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is m.block<2,2>(1,1):" << endl << m.block<2,2>(1,1) << endl;
m.block<2,2>(1,1).setZero();
cout << "Now the matrix m is:" << endl << m << endl;

Output:

Here is the matrix m:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is m.block<2,2>(1,1):
-6 1
-3 0
Now the matrix m is:
 7  9 -5 -3
-2  0  0  0
 6  0  0  9
 6  6  3  9
Note
since block is a templated member, the keyword template has to be used if the matrix type is also a template parameter:
m.template block<3,3>(1,1);
See Also
class Block, block(Index,Index,Index,Index)
const Block<const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , BlockRows, BlockCols> block ( Index  startRow,
Index  startCol 
) const
inlineinherited

This is the const version of block<>(Index, Index).

Block<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , BlockRows, BlockCols> block ( Index  startRow,
Index  startCol,
Index  blockRows,
Index  blockCols 
)
inlineinherited
Returns
an expression of a block in *this.
Template Parameters
BlockRowsnumber of rows in block as specified at compile time
BlockColsnumber of columns in block as specified at compile time
Parameters
startRowthe first row in the block
startColthe first column in the block
blockRowsnumber of rows in block as specified at run time
blockColsnumber of columns in block as specified at run time

This function is mainly useful for blocks where the number of rows is specified at compile time and the number of columns is specified at run time, or vice versa. The compile-time and run-time information should not contradict. In other words, blockRows should equal BlockRows unless BlockRows is Dynamic, and the same for the number of columns.

Example:

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is the block:" << endl << m.block<2, Dynamic>(1, 1, 2, 3) << endl;
m.block<2, Dynamic>(1, 1, 2, 3).setZero();
cout << "Now the matrix m is:" << endl << m << endl;

Output:

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is the block:" << endl << m.block<2, Dynamic>(1, 1, 2, 3) << endl;
m.block<2, Dynamic>(1, 1, 2, 3).setZero();
cout << "Now the matrix m is:" << endl << m << endl;
See Also
class Block, block(Index,Index,Index,Index)
const Block<const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , BlockRows, BlockCols> block ( Index  startRow,
Index  startCol,
Index  blockRows,
Index  blockCols 
) const
inlineinherited

This is the const version of block<>(Index, Index, Index, Index).

Block<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > bottomLeftCorner ( Index  cRows,
Index  cCols 
)
inlineinherited
Returns
a dynamic-size expression of a bottom-left corner of *this.
Parameters
cRowsthe number of rows in the corner
cColsthe number of columns in the corner

Example:

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is m.bottomLeftCorner(2, 2):" << endl;
cout << m.bottomLeftCorner(2, 2) << endl;
m.bottomLeftCorner(2, 2).setZero();
cout << "Now the matrix m is:" << endl << m << endl;

Output:

Here is the matrix m:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is m.bottomLeftCorner(2, 2):
 6 -3
 6  6
Now the matrix m is:
 7  9 -5 -3
-2 -6  1  0
 0  0  0  9
 0  0  3  9
See Also
class Block, block(Index,Index,Index,Index)
const Block<const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > bottomLeftCorner ( Index  cRows,
Index  cCols 
) const
inlineinherited

This is the const version of bottomLeftCorner(Index, Index).

Block<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , CRows, CCols> bottomLeftCorner ( )
inlineinherited
Returns
an expression of a fixed-size bottom-left corner of *this.

The template parameters CRows and CCols are the number of rows and columns in the corner.

Example:

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is m.bottomLeftCorner<2,2>():" << endl;
cout << m.bottomLeftCorner<2,2>() << endl;
m.bottomLeftCorner<2,2>().setZero();
cout << "Now the matrix m is:" << endl << m << endl;

Output:

Here is the matrix m:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is m.bottomLeftCorner<2,2>():
 6 -3
 6  6
Now the matrix m is:
 7  9 -5 -3
-2 -6  1  0
 0  0  0  9
 0  0  3  9
See Also
class Block, block(Index,Index,Index,Index)
const Block<const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , CRows, CCols> bottomLeftCorner ( ) const
inlineinherited

This is the const version of bottomLeftCorner<int, int>().

Block<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , CRows, CCols> bottomLeftCorner ( Index  cRows,
Index  cCols 
)
inlineinherited
Returns
an expression of a bottom-left corner of *this.
Template Parameters
CRowsnumber of rows in corner as specified at compile time
CColsnumber of columns in corner as specified at compile time
Parameters
cRowsnumber of rows in corner as specified at run time
cColsnumber of columns in corner as specified at run time

This function is mainly useful for corners where the number of rows is specified at compile time and the number of columns is specified at run time, or vice versa. The compile-time and run-time information should not contradict. In other words, cRows should equal CRows unless CRows is Dynamic, and the same for the number of columns.

Example:

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is m.bottomLeftCorner<2,Dynamic>(2,2):" << endl;
cout << m.bottomLeftCorner<2,Dynamic>(2,2) << endl;
m.bottomLeftCorner<2,Dynamic>(2,2).setZero();
cout << "Now the matrix m is:" << endl << m << endl;

Output:

Here is the matrix m:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is m.bottomLeftCorner<2,Dynamic>(2,2):
 6 -3
 6  6
Now the matrix m is:
 7  9 -5 -3
-2 -6  1  0
 0  0  0  9
 0  0  3  9
See Also
class Block
const Block<const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , CRows, CCols> bottomLeftCorner ( Index  cRows,
Index  cCols 
) const
inlineinherited

This is the const version of bottomLeftCorner<int, int>(Index, Index).

Block<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > bottomRightCorner ( Index  cRows,
Index  cCols 
)
inlineinherited
Returns
a dynamic-size expression of a bottom-right corner of *this.
Parameters
cRowsthe number of rows in the corner
cColsthe number of columns in the corner

Example:

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is m.bottomRightCorner(2, 2):" << endl;
cout << m.bottomRightCorner(2, 2) << endl;
m.bottomRightCorner(2, 2).setZero();
cout << "Now the matrix m is:" << endl << m << endl;

Output:

Here is the matrix m:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is m.bottomRightCorner(2, 2):
0 9
3 9
Now the matrix m is:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  0
 6  6  0  0
See Also
class Block, block(Index,Index,Index,Index)
const Block<const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > bottomRightCorner ( Index  cRows,
Index  cCols 
) const
inlineinherited

This is the const version of bottomRightCorner(Index, Index).

Block<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , CRows, CCols> bottomRightCorner ( )
inlineinherited
Returns
an expression of a fixed-size bottom-right corner of *this.

The template parameters CRows and CCols are the number of rows and columns in the corner.

Example:

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is m.bottomRightCorner<2,2>():" << endl;
cout << m.bottomRightCorner<2,2>() << endl;
m.bottomRightCorner<2,2>().setZero();
cout << "Now the matrix m is:" << endl << m << endl;

Output:

Here is the matrix m:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is m.bottomRightCorner<2,2>():
0 9
3 9
Now the matrix m is:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  0
 6  6  0  0
See Also
class Block, block(Index,Index,Index,Index)
const Block<const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , CRows, CCols> bottomRightCorner ( ) const
inlineinherited

This is the const version of bottomRightCorner<int, int>().

Block<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , CRows, CCols> bottomRightCorner ( Index  cRows,
Index  cCols 
)
inlineinherited
Returns
an expression of a bottom-right corner of *this.
Template Parameters
CRowsnumber of rows in corner as specified at compile time
CColsnumber of columns in corner as specified at compile time
Parameters
cRowsnumber of rows in corner as specified at run time
cColsnumber of columns in corner as specified at run time

This function is mainly useful for corners where the number of rows is specified at compile time and the number of columns is specified at run time, or vice versa. The compile-time and run-time information should not contradict. In other words, cRows should equal CRows unless CRows is Dynamic, and the same for the number of columns.

Example:

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is m.bottomRightCorner<2,Dynamic>(2,2):" << endl;
cout << m.bottomRightCorner<2,Dynamic>(2,2) << endl;
m.bottomRightCorner<2,Dynamic>(2,2).setZero();
cout << "Now the matrix m is:" << endl << m << endl;

Output:

Here is the matrix m:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is m.bottomRightCorner<2,Dynamic>(2,2):
0 9
3 9
Now the matrix m is:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  0
 6  6  0  0
See Also
class Block
const Block<const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , CRows, CCols> bottomRightCorner ( Index  cRows,
Index  cCols 
) const
inlineinherited

This is the const version of bottomRightCorner<int, int>(Index, Index).

RowsBlockXpr bottomRows ( Index  n)
inlineinherited
Returns
a block consisting of the bottom rows of *this.
Parameters
nthe number of rows in the block

Example:

Array44i a = Array44i::Random();
cout << "Here is the array a:" << endl << a << endl;
cout << "Here is a.bottomRows(2):" << endl;
cout << a.bottomRows(2) << endl;
a.bottomRows(2).setZero();
cout << "Now the array a is:" << endl << a << endl;

Output:

Here is the array a:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is a.bottomRows(2):
 6 -3  0  9
 6  6  3  9
Now the array a is:
 7  9 -5 -3
-2 -6  1  0
 0  0  0  0
 0  0  0  0
See Also
class Block, block(Index,Index,Index,Index)
ConstRowsBlockXpr bottomRows ( Index  n) const
inlineinherited

This is the const version of bottomRows(Index).

NRowsBlockXpr<N>::Type bottomRows ( )
inlineinherited
Returns
a block consisting of the bottom rows of *this.
Template Parameters
Nthe number of rows in the block

Example:

Array44i a = Array44i::Random();
cout << "Here is the array a:" << endl << a << endl;
cout << "Here is a.bottomRows<2>():" << endl;
cout << a.bottomRows<2>() << endl;
a.bottomRows<2>().setZero();
cout << "Now the array a is:" << endl << a << endl;

Output:

Here is the array a:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is a.bottomRows<2>():
 6 -3  0  9
 6  6  3  9
Now the array a is:
 7  9 -5 -3
-2 -6  1  0
 0  0  0  0
 0  0  0  0
See Also
class Block, block(Index,Index,Index,Index)
ConstNRowsBlockXpr<N>::Type bottomRows ( ) const
inlineinherited

This is the const version of bottomRows<int>().

internal::cast_return_type<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > ,const CwiseUnaryOp<internal::scalar_cast_op<typename internal::traits<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > >::Scalar, NewType>, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > >::type cast ( ) const
inlineinherited
Returns
an expression of *this with the Scalar type casted to NewScalar.

The template parameter NewScalar is the type we are casting the scalars to.

See Also
class CwiseUnaryOp
ColXpr col ( Index  i)
inlineinherited
Returns
an expression of the i-th column of *this. Note that the numbering starts at 0.

Example:

Matrix3d m = Matrix3d::Identity();
m.col(1) = Vector3d(4,5,6);
cout << m << endl;

Output:

1 4 0
0 5 0
0 6 1
See Also
row(), class Block
ConstColXpr col ( Index  i) const
inlineinherited

This is the const version of col().

ConjugateReturnType conjugate ( ) const
inlineinherited
Returns
an expression of the complex conjugate of *this.
See Also
adjoint()
void conservativeResize ( Index  nbRows,
Index  nbCols 
)
inlineinherited

Resizes the matrix to rows x cols while leaving old values untouched.

The method is intended for matrices of dynamic size. If you only want to change the number of rows and/or of columns, you can use conservativeResize(NoChange_t, Index) or conservativeResize(Index, NoChange_t).

Matrices are resized relative to the top-left element. In case values need to be appended to the matrix they will be uninitialized.

void conservativeResize ( Index  nbRows,
NoChange_t   
)
inlineinherited

Resizes the matrix to rows x cols while leaving old values untouched.

As opposed to conservativeResize(Index rows, Index cols), this version leaves the number of columns unchanged.

In case the matrix is growing, new rows will be uninitialized.

void conservativeResize ( NoChange_t  ,
Index  nbCols 
)
inlineinherited

Resizes the matrix to rows x cols while leaving old values untouched.

As opposed to conservativeResize(Index rows, Index cols), this version leaves the number of rows unchanged.

In case the matrix is growing, new columns will be uninitialized.

void conservativeResize ( Index  size)
inlineinherited

Resizes the vector to size while retaining old values.

This is only for vectors (either row-vectors or column-vectors), i.e. matrices which are known at compile-time to have either one row or one column.. This method does not work for partially dynamic matrices when the static dimension is anything other than 1. For example it will not work with Matrix<double, 2, Dynamic>.

When values are appended, they will be uninitialized.

void conservativeResizeLike ( const DenseBase< OtherDerived > &  other)
inlineinherited

Resizes the matrix to rows x cols of other, while leaving old values untouched.

The method is intended for matrices of dynamic size. If you only want to change the number of rows and/or of columns, you can use conservativeResize(NoChange_t, Index) or conservativeResize(Index, NoChange_t).

Matrices are resized relative to the top-left element. In case values need to be appended to the matrix they will copied from other.

const CwiseUnaryOp<internal::scalar_abs_op<Scalar>, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > cwiseAbs ( ) const
inlineinherited
Returns
an expression of the coefficient-wise absolute value of *this

Example:

MatrixXd m(2,3);
m << 2, -4, 6,
-5, 1, 0;
cout << m.cwiseAbs() << endl;

Output:

2 4 6
5 1 0
See Also
cwiseAbs2()
const CwiseUnaryOp<internal::scalar_abs2_op<Scalar>, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > cwiseAbs2 ( ) const
inlineinherited
Returns
an expression of the coefficient-wise squared absolute value of *this

Example:

MatrixXd m(2,3);
m << 2, -4, 6,
-5, 1, 0;
cout << m.cwiseAbs2() << endl;

Output:

 4 16 36
25  1  0
See Also
cwiseAbs()
const CwiseBinaryOp<std::equal_to<Scalar>, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , const OtherDerived> cwiseEqual ( const Eigen::MatrixBase< OtherDerived > &  other) const
inlineinherited
Returns
an expression of the coefficient-wise == operator of *this and other
Warning
this performs an exact comparison, which is generally a bad idea with floating-point types. In order to check for equality between two vectors or matrices with floating-point coefficients, it is generally a far better idea to use a fuzzy comparison as provided by isApprox() and isMuchSmallerThan().

Example:

MatrixXi m(2,2);
m << 1, 0,
1, 1;
cout << "Comparing m with identity matrix:" << endl;
cout << m.cwiseEqual(MatrixXi::Identity(2,2)) << endl;
int count = m.cwiseEqual(MatrixXi::Identity(2,2)).count();
cout << "Number of coefficients that are equal: " << count << endl;

Output:

Comparing m with identity matrix:
1 1
0 1
Number of coefficients that are equal: 3
See Also
cwiseNotEqual(), isApprox(), isMuchSmallerThan()
const CwiseUnaryOp<std::binder1st<std::equal_to<Scalar> >, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > cwiseEqual ( const Scalar &  s) const
inlineinherited
Returns
an expression of the coefficient-wise == operator of *this and a scalar s
Warning
this performs an exact comparison, which is generally a bad idea with floating-point types. In order to check for equality between two vectors or matrices with floating-point coefficients, it is generally a far better idea to use a fuzzy comparison as provided by isApprox() and isMuchSmallerThan().
See Also
cwiseEqual(const MatrixBase<OtherDerived> &) const
const CwiseUnaryOp<internal::scalar_inverse_op<Scalar>, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > cwiseInverse ( ) const
inlineinherited
Returns
an expression of the coefficient-wise inverse of *this.

Example:

MatrixXd m(2,3);
m << 2, 0.5, 1,
3, 0.25, 1;
cout << m.cwiseInverse() << endl;

Output:

0.5 2 1
0.333 4 1
See Also
cwiseProduct()
const CwiseBinaryOp<internal::scalar_max_op<Scalar>, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , const OtherDerived> cwiseMax ( const Eigen::MatrixBase< OtherDerived > &  other) const
inlineinherited
Returns
an expression of the coefficient-wise max of *this and other

Example:

Vector3d v(2,3,4), w(4,2,3);
cout << v.cwiseMax(w) << endl;

Output:

4
3
4
See Also
class CwiseBinaryOp, min()
const CwiseBinaryOp<internal::scalar_max_op<Scalar>, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , const ConstantReturnType> cwiseMax ( const Scalar &  other) const
inlineinherited
Returns
an expression of the coefficient-wise max of *this and scalar other
See Also
class CwiseBinaryOp, min()
const CwiseBinaryOp<internal::scalar_min_op<Scalar>, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , const OtherDerived> cwiseMin ( const Eigen::MatrixBase< OtherDerived > &  other) const
inlineinherited
Returns
an expression of the coefficient-wise min of *this and other

Example:

Vector3d v(2,3,4), w(4,2,3);
cout << v.cwiseMin(w) << endl;

Output:

2
2
3
See Also
class CwiseBinaryOp, max()
const CwiseBinaryOp<internal::scalar_min_op<Scalar>, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , const ConstantReturnType> cwiseMin ( const Scalar &  other) const
inlineinherited
Returns
an expression of the coefficient-wise min of *this and scalar other
See Also
class CwiseBinaryOp, min()
const CwiseBinaryOp<std::not_equal_to<Scalar>, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , const OtherDerived> cwiseNotEqual ( const Eigen::MatrixBase< OtherDerived > &  other) const
inlineinherited
Returns
an expression of the coefficient-wise != operator of *this and other
Warning
this performs an exact comparison, which is generally a bad idea with floating-point types. In order to check for equality between two vectors or matrices with floating-point coefficients, it is generally a far better idea to use a fuzzy comparison as provided by isApprox() and isMuchSmallerThan().

Example:

MatrixXi m(2,2);
m << 1, 0,
1, 1;
cout << "Comparing m with identity matrix:" << endl;
cout << m.cwiseNotEqual(MatrixXi::Identity(2,2)) << endl;
int count = m.cwiseNotEqual(MatrixXi::Identity(2,2)).count();
cout << "Number of coefficients that are not equal: " << count << endl;

Output:

Comparing m with identity matrix:
0 0
1 0
Number of coefficients that are not equal: 1
See Also
cwiseEqual(), isApprox(), isMuchSmallerThan()
const CwiseBinaryOp<internal::scalar_product_op<typename Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > ::Scalar, typename OtherDerived ::Scalar >, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , const OtherDerived > cwiseProduct ( const Eigen::MatrixBase< OtherDerived > &  other) const
inlineinherited
Returns
an expression of the Schur product (coefficient wise product) of *this and other

Example:

Matrix3i a = Matrix3i::Random(), b = Matrix3i::Random();
Matrix3i c = a.cwiseProduct(b);
cout << "a:\n" << a << "\nb:\n" << b << "\nc:\n" << c << endl;

Output:

a:
 7  6 -3
-2  9  6
 6 -6 -5
b:
 1 -3  9
 0  0  3
 3  9  5
c:
  7 -18 -27
  0   0  18
 18 -54 -25
See Also
class CwiseBinaryOp, cwiseAbs2
const CwiseBinaryOp<internal::scalar_quotient_op<Scalar>, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , const OtherDerived> cwiseQuotient ( const Eigen::MatrixBase< OtherDerived > &  other) const
inlineinherited
Returns
an expression of the coefficient-wise quotient of *this and other

Example:

Vector3d v(2,3,4), w(4,2,3);
cout << v.cwiseQuotient(w) << endl;

Output:

0.5
1.5
1.33
See Also
class CwiseBinaryOp, cwiseProduct(), cwiseInverse()
const CwiseUnaryOp<internal::scalar_sqrt_op<Scalar>, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > cwiseSqrt ( ) const
inlineinherited
Returns
an expression of the coefficient-wise square root of *this.

Example:

Vector3d v(1,2,4);
cout << v.cwiseSqrt() << endl;

Output:

1
1.41
2
See Also
cwisePow(), cwiseSquare()
const Scalar* data ( ) const
inlineinherited
Returns
a const pointer to the data array of this matrix
Scalar* data ( )
inlineinherited
Returns
a pointer to the data array of this matrix
Index diagonalSize ( ) const
inlineinherited
Returns
the size of the main diagonal, which is min(rows(),cols()).
See Also
rows(), cols(), SizeAtCompileTime.
EvalReturnType eval ( ) const
inlineinherited
Returns
the matrix or vector obtained by evaluating this expression.

Notice that in the case of a plain matrix or vector (not an expression) this function just returns a const reference, in order to avoid a useless copy.

SegmentReturnType head ( Index  vecSize)
inlineinherited
Returns
a dynamic-size expression of the first coefficients of *this.

This is only for vectors (either row-vectors or column-vectors), i.e. matrices which are known at compile-time to have either one row or one column.

Parameters
vecSizethe number of coefficients in the block

Example:

RowVector4i v = RowVector4i::Random();
cout << "Here is the vector v:" << endl << v << endl;
cout << "Here is v.head(2):" << endl << v.head(2) << endl;
v.head(2).setZero();
cout << "Now the vector v is:" << endl << v << endl;

Output:

Here is the vector v:
 7 -2  6  6
Here is v.head(2):
 7 -2
Now the vector v is:
0 0 6 6
Note
Even though the returned expression has dynamic size, in the case when it is applied to a fixed-size vector, it inherits a fixed maximal size, which means that evaluating it does not cause a dynamic memory allocation.
See Also
class Block, block(Index,Index)
ConstSegmentReturnType head ( Index  vecSize) const
inlineinherited

This is the const version of head(Index).

FixedSegmentReturnType<Size>::Type head ( )
inlineinherited
Returns
a fixed-size expression of the first coefficients of *this.

This is only for vectors (either row-vectors or column-vectors), i.e. matrices which are known at compile-time to have either one row or one column.

The template parameter Size is the number of coefficients in the block

Example:

RowVector4i v = RowVector4i::Random();
cout << "Here is the vector v:" << endl << v << endl;
cout << "Here is v.head(2):" << endl << v.head<2>() << endl;
v.head<2>().setZero();
cout << "Now the vector v is:" << endl << v << endl;

Output:

Here is the vector v:
 7 -2  6  6
Here is v.head(2):
 7 -2
Now the vector v is:
0 0 6 6
See Also
class Block
ConstFixedSegmentReturnType<Size>::Type head ( ) const
inlineinherited

This is the const version of head<int>().

const ImagReturnType imag ( ) const
inlineinherited
Returns
an read-only expression of the imaginary part of *this.
See Also
real()
NonConstImagReturnType imag ( )
inlineinherited
Returns
a non const expression of the imaginary part of *this.
See Also
real()
Index innerSize ( ) const
inlineinherited
Returns
the inner size.
Note
For a vector, this is just the size. For a matrix (non-vector), this is the minor dimension with respect to the storage order, i.e., the number of rows for a column-major matrix, and the number of columns for a row-major matrix.
Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > & lazyAssign ( const DenseBase< OtherDerived > &  other)
inlineinherited
See Also
MatrixBase::lazyAssign()
ColsBlockXpr leftCols ( Index  n)
inlineinherited
Returns
a block consisting of the left columns of *this.
Parameters
nthe number of columns in the block

Example:

Array44i a = Array44i::Random();
cout << "Here is the array a:" << endl << a << endl;
cout << "Here is a.leftCols(2):" << endl;
cout << a.leftCols(2) << endl;
a.leftCols(2).setZero();
cout << "Now the array a is:" << endl << a << endl;

Output:

Here is the array a:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is a.leftCols(2):
 7  9
-2 -6
 6 -3
 6  6
Now the array a is:
 0  0 -5 -3
 0  0  1  0
 0  0  0  9
 0  0  3  9
See Also
class Block, block(Index,Index,Index,Index)
ConstColsBlockXpr leftCols ( Index  n) const
inlineinherited

This is the const version of leftCols(Index).

NColsBlockXpr<N>::Type leftCols ( )
inlineinherited
Returns
a block consisting of the left columns of *this.
Template Parameters
Nthe number of columns in the block

Example:

Array44i a = Array44i::Random();
cout << "Here is the array a:" << endl << a << endl;
cout << "Here is a.leftCols<2>():" << endl;
cout << a.leftCols<2>() << endl;
a.leftCols<2>().setZero();
cout << "Now the array a is:" << endl << a << endl;

Output:

Here is the array a:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is a.leftCols<2>():
 7  9
-2 -6
 6 -3
 6  6
Now the array a is:
 0  0 -5 -3
 0  0  1  0
 0  0  0  9
 0  0  3  9
See Also
class Block, block(Index,Index,Index,Index)
ConstNColsBlockXpr<N>::Type leftCols ( ) const
inlineinherited

This is the const version of leftCols<int>().

ColsBlockXpr middleCols ( Index  startCol,
Index  numCols 
)
inlineinherited
Returns
a block consisting of a range of columns of *this.
Parameters
startColthe index of the first column in the block
numColsthe number of columns in the block

Example:

#include <Eigen/Core>
#include <iostream>
using namespace Eigen;
using namespace std;
int main(void)
{
int const N = 5;
MatrixXi A(N,N);
A.setRandom();
cout << "A =\n" << A << '\n' << endl;
cout << "A(1..3,:) =\n" << A.middleCols(1,3) << endl;
return 0;
}

Output:

A =
  7  -6   0   9 -10
 -2  -3   3   3  -5
  6   6  -3   5  -8
  6  -5   0  -8   6
  9   1   9   2  -7

A(1..3,:) =
-6  0  9
-3  3  3
 6 -3  5
-5  0 -8
 1  9  2
See Also
class Block, block(Index,Index,Index,Index)
ConstColsBlockXpr middleCols ( Index  startCol,
Index  numCols 
) const
inlineinherited

This is the const version of middleCols(Index,Index).

NColsBlockXpr<N>::Type middleCols ( Index  startCol)
inlineinherited
Returns
a block consisting of a range of columns of *this.
Template Parameters
Nthe number of columns in the block
Parameters
startColthe index of the first column in the block

Example:

#include <Eigen/Core>
#include <iostream>
using namespace Eigen;
using namespace std;
int main(void)
{
int const N = 5;
MatrixXi A(N,N);
A.setRandom();
cout << "A =\n" << A << '\n' << endl;
cout << "A(:,1..3) =\n" << A.middleCols<3>(1) << endl;
return 0;
}

Output:

A =
  7  -6   0   9 -10
 -2  -3   3   3  -5
  6   6  -3   5  -8
  6  -5   0  -8   6
  9   1   9   2  -7

A(:,1..3) =
-6  0  9
-3  3  3
 6 -3  5
-5  0 -8
 1  9  2
See Also
class Block, block(Index,Index,Index,Index)
ConstNColsBlockXpr<N>::Type middleCols ( Index  startCol) const
inlineinherited

This is the const version of middleCols<int>().

RowsBlockXpr middleRows ( Index  startRow,
Index  numRows 
)
inlineinherited
Returns
a block consisting of a range of rows of *this.
Parameters
startRowthe index of the first row in the block
numRowsthe number of rows in the block

Example:

#include <Eigen/Core>
#include <iostream>
using namespace Eigen;
using namespace std;
int main(void)
{
int const N = 5;
MatrixXi A(N,N);
A.setRandom();
cout << "A =\n" << A << '\n' << endl;
cout << "A(2..3,:) =\n" << A.middleRows(2,2) << endl;
return 0;
}

Output:

A =
  7  -6   0   9 -10
 -2  -3   3   3  -5
  6   6  -3   5  -8
  6  -5   0  -8   6
  9   1   9   2  -7

A(2..3,:) =
 6  6 -3  5 -8
 6 -5  0 -8  6
See Also
class Block, block(Index,Index,Index,Index)
ConstRowsBlockXpr middleRows ( Index  startRow,
Index  numRows 
) const
inlineinherited

This is the const version of middleRows(Index,Index).

NRowsBlockXpr<N>::Type middleRows ( Index  startRow)
inlineinherited
Returns
a block consisting of a range of rows of *this.
Template Parameters
Nthe number of rows in the block
Parameters
startRowthe index of the first row in the block

Example:

#include <Eigen/Core>
#include <iostream>
using namespace Eigen;
using namespace std;
int main(void)
{
int const N = 5;
MatrixXi A(N,N);
A.setRandom();
cout << "A =\n" << A << '\n' << endl;
cout << "A(1..3,:) =\n" << A.middleRows<3>(1) << endl;
return 0;
}

Output:

A =
  7  -6   0   9 -10
 -2  -3   3   3  -5
  6   6  -3   5  -8
  6  -5   0  -8   6
  9   1   9   2  -7

A(1..3,:) =
-2 -3  3  3 -5
 6  6 -3  5 -8
 6 -5  0 -8  6
See Also
class Block, block(Index,Index,Index,Index)
ConstNRowsBlockXpr<N>::Type middleRows ( Index  startRow) const
inlineinherited

This is the const version of middleRows<int>().

Index nonZeros ( ) const
inlineinherited
Returns
the number of nonzero coefficients which is in practice the number of stored coefficients.
bool operator!= ( const MatrixBase< OtherDerived > &  other) const
inlineinherited
Returns
true if at least one pair of coefficients of *this and other are not exactly equal to each other.
Warning
When using floating point scalar values you probably should rather use a fuzzy comparison such as isApprox()
See Also
isApprox(), operator==
const ScalarMultipleReturnType operator* ( const Scalar &  scalar) const
inlineinherited
Returns
an expression of *this scaled by the scalar factor scalar
const CwiseUnaryOp<internal::scalar_multiple2_op<Scalar,std::complex<Scalar> >, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > operator* ( const std::complex< Scalar > &  scalar) const
inlineinherited

Overloaded for efficient real matrix times complex scalar value

const CwiseBinaryOp< internal::scalar_sum_op <Scalar>, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , const OtherDerived> operator+ ( const Eigen::MatrixBase< OtherDerived > &  other) const
inherited
Returns
an expression of the sum of *this and other
Note
If you want to add a given scalar to all coefficients, see Cwise::operator+().
See Also
class CwiseBinaryOp, operator+=()
const CwiseBinaryOp< internal::scalar_difference_op <Scalar>, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , const OtherDerived> operator- ( const Eigen::MatrixBase< OtherDerived > &  other) const
inherited
Returns
an expression of the difference of *this and other
Note
If you want to substract a given scalar from all coefficients, see Cwise::operator-().
See Also
class CwiseBinaryOp, operator-=()
const CwiseUnaryOp<internal::scalar_opposite_op<typename internal::traits<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > >::Scalar>, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > operator- ( ) const
inlineinherited
Returns
an expression of the opposite of *this
const CwiseUnaryOp<internal::scalar_quotient1_op<typename internal::traits<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > >::Scalar>, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > operator/ ( const Scalar &  scalar) const
inlineinherited
Returns
an expression of *this divided by the scalar value scalar
Matrix& operator= ( const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > &  other)
inline

Assigns matrices to each other.

Note
This is a special case of the templated operator=. Its purpose is to prevent a default operator= from hiding the templated operator=.
Matrix& operator= ( const EigenBase< OtherDerived > &  other)
inline

Copies the generic expression other into *this.

The expression must provide a (templated) evalTo(Derived& dst) const function which does the actual job. In practice, this allows any user to write its own special matrix without having to modify MatrixBase

Returns
a reference to *this.

Reimplemented from PlainObjectBase< Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > >.

Matrix< _Scalar, _Rows, _Cols, _Storage, _MaxRows, _MaxCols > & operator= ( const RotationBase< OtherDerived, ColsAtCompileTime > &  r)

Set a Dim x Dim rotation matrix from the rotation r.

This is defined in the Geometry module.

#include <Eigen/Geometry>

References RotationBase< Derived, _Dim >::toRotationMatrix().

bool operator== ( const MatrixBase< OtherDerived > &  other) const
inlineinherited
Returns
true if each coefficients of *this and other are all exactly equal.
Warning
When using floating point scalar values you probably should rather use a fuzzy comparison such as isApprox()
See Also
isApprox(), operator!=
Index outerSize ( ) const
inlineinherited
Returns
true if either the number of rows or the number of columns is equal to 1. In other words, this function returns
rows()==1 || cols()==1
See Also
rows(), cols(), IsVectorAtCompileTime.
Returns
the outer size.
Note
For a vector, this returns just 1. For a matrix (non-vector), this is the major dimension with respect to the storage order, i.e., the number of columns for a column-major matrix, and the number of rows for a row-major matrix.
RealReturnType real ( ) const
inlineinherited
Returns
a read-only expression of the real part of *this.
See Also
imag()
NonConstRealReturnType real ( )
inlineinherited
Returns
a non const expression of the real part of *this.
See Also
imag()
void resize ( Index  nbRows,
Index  nbCols 
)
inlineinherited

Resizes *this to a rows x cols matrix.

This method is intended for dynamic-size matrices, although it is legal to call it on any matrix as long as fixed dimensions are left unchanged. If you only want to change the number of rows and/or of columns, you can use resize(NoChange_t, Index), resize(Index, NoChange_t).

If the current number of coefficients of *this exactly matches the product rows * cols, then no memory allocation is performed and the current values are left unchanged. In all other cases, including shrinking, the data is reallocated and all previous values are lost.

Example:

MatrixXd m(2,3);
m << 1,2,3,4,5,6;
cout << "here's the 2x3 matrix m:" << endl << m << endl;
cout << "let's resize m to 3x2. This is a conservative resizing because 2*3==3*2." << endl;
m.resize(3,2);
cout << "here's the 3x2 matrix m:" << endl << m << endl;
cout << "now let's resize m to size 2x2. This is NOT a conservative resizing, so it becomes uninitialized:" << endl;
m.resize(2,2);
cout << m << endl;

Output:

here's the 2x3 matrix m:
1 2 3
4 5 6
let's resize m to 3x2. This is a conservative resizing because 2*3==3*2.
here's the 3x2 matrix m:
1 5
4 3
2 6
now let's resize m to size 2x2. This is NOT a conservative resizing, so it becomes uninitialized:
2.34e-310 2.12e-314
4.94e-324 4.94e-323
See Also
resize(Index) for vectors, resize(NoChange_t, Index), resize(Index, NoChange_t)

Reimplemented from DenseBase< Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > >.

void resize ( Index  size)
inlineinherited

Resizes *this to a vector of length size

This is only for vectors (either row-vectors or column-vectors), i.e. matrices which are known at compile-time to have either one row or one column.. This method does not work for partially dynamic matrices when the static dimension is anything other than 1. For example it will not work with Matrix<double, 2, Dynamic>.

Example:

VectorXd v(10);
v.resize(3);
w.resize(3); // this is legal, but has no effect
cout << "v: " << v.rows() << " rows, " << v.cols() << " cols" << endl;
cout << "w: " << w.rows() << " rows, " << w.cols() << " cols" << endl;

Output:

v: 3 rows, 1 cols
w: 1 rows, 3 cols
See Also
resize(Index,Index), resize(NoChange_t, Index), resize(Index, NoChange_t)

Reimplemented from DenseBase< Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > >.

void resize ( NoChange_t  ,
Index  nbCols 
)
inlineinherited

Resizes the matrix, changing only the number of columns. For the parameter of type NoChange_t, just pass the special value NoChange as in the example below.

Example:

MatrixXd m(3,4);
m.resize(NoChange, 5);
cout << "m: " << m.rows() << " rows, " << m.cols() << " cols" << endl;

Output:

m: 3 rows, 5 cols
See Also
resize(Index,Index)
void resize ( Index  nbRows,
NoChange_t   
)
inlineinherited

Resizes the matrix, changing only the number of rows. For the parameter of type NoChange_t, just pass the special value NoChange as in the example below.

Example:

MatrixXd m(3,4);
m.resize(5, NoChange);
cout << "m: " << m.rows() << " rows, " << m.cols() << " cols" << endl;

Output:

m: 5 rows, 4 cols
See Also
resize(Index,Index)
void resizeLike ( const EigenBase< OtherDerived > &  _other)
inlineinherited

Resizes *this to have the same dimensions as other. Takes care of doing all the checking that's needed.

Note that copying a row-vector into a vector (and conversely) is allowed. The resizing, if any, is then done in the appropriate way so that row-vectors remain row-vectors and vectors remain vectors.

ColsBlockXpr rightCols ( Index  n)
inlineinherited
Returns
a block consisting of the right columns of *this.
Parameters
nthe number of columns in the block

Example:

Array44i a = Array44i::Random();
cout << "Here is the array a:" << endl << a << endl;
cout << "Here is a.rightCols(2):" << endl;
cout << a.rightCols(2) << endl;
a.rightCols(2).setZero();
cout << "Now the array a is:" << endl << a << endl;

Output:

Here is the array a:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is a.rightCols(2):
-5 -3
 1  0
 0  9
 3  9
Now the array a is:
 7  9  0  0
-2 -6  0  0
 6 -3  0  0
 6  6  0  0
See Also
class Block, block(Index,Index,Index,Index)
ConstColsBlockXpr rightCols ( Index  n) const
inlineinherited

This is the const version of rightCols(Index).

NColsBlockXpr<N>::Type rightCols ( )
inlineinherited
Returns
a block consisting of the right columns of *this.
Template Parameters
Nthe number of columns in the block

Example:

Array44i a = Array44i::Random();
cout << "Here is the array a:" << endl << a << endl;
cout << "Here is a.rightCols<2>():" << endl;
cout << a.rightCols<2>() << endl;
a.rightCols<2>().setZero();
cout << "Now the array a is:" << endl << a << endl;

Output:

Here is the array a:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is a.rightCols<2>():
-5 -3
 1  0
 0  9
 3  9
Now the array a is:
 7  9  0  0
-2 -6  0  0
 6 -3  0  0
 6  6  0  0
See Also
class Block, block(Index,Index,Index,Index)
ConstNColsBlockXpr<N>::Type rightCols ( ) const
inlineinherited

This is the const version of rightCols<int>().

RowXpr row ( Index  i)
inlineinherited
Returns
an expression of the i-th row of *this. Note that the numbering starts at 0.

Example:

Matrix3d m = Matrix3d::Identity();
m.row(1) = Vector3d(4,5,6);
cout << m << endl;

Output:

1 0 0
4 5 6
0 0 1
See Also
col(), class Block
ConstRowXpr row ( Index  i) const
inlineinherited

This is the const version of row().

SegmentReturnType segment ( Index  start,
Index  vecSize 
)
inlineinherited
Returns
a dynamic-size expression of a segment (i.e. a vector block) in *this.

This is only for vectors (either row-vectors or column-vectors), i.e. matrices which are known at compile-time to have either one row or one column.

Parameters
startthe first coefficient in the segment
vecSizethe number of coefficients in the segment

Example:

RowVector4i v = RowVector4i::Random();
cout << "Here is the vector v:" << endl << v << endl;
cout << "Here is v.segment(1, 2):" << endl << v.segment(1, 2) << endl;
v.segment(1, 2).setZero();
cout << "Now the vector v is:" << endl << v << endl;

Output:

Here is the vector v:
 7 -2  6  6
Here is v.segment(1, 2):
-2 6
Now the vector v is:
7 0 0 6
Note
Even though the returned expression has dynamic size, in the case when it is applied to a fixed-size vector, it inherits a fixed maximal size, which means that evaluating it does not cause a dynamic memory allocation.
See Also
class Block, segment(Index)
ConstSegmentReturnType segment ( Index  start,
Index  vecSize 
) const
inlineinherited

This is the const version of segment(Index,Index).

FixedSegmentReturnType<Size>::Type segment ( Index  start)
inlineinherited
Returns
a fixed-size expression of a segment (i.e. a vector block) in *this

This is only for vectors (either row-vectors or column-vectors), i.e. matrices which are known at compile-time to have either one row or one column.

The template parameter Size is the number of coefficients in the block

Parameters
startthe index of the first element of the sub-vector

Example:

RowVector4i v = RowVector4i::Random();
cout << "Here is the vector v:" << endl << v << endl;
cout << "Here is v.segment<2>(1):" << endl << v.segment<2>(1) << endl;
v.segment<2>(2).setZero();
cout << "Now the vector v is:" << endl << v << endl;

Output:

Here is the vector v:
 7 -2  6  6
Here is v.segment<2>(1):
-2 6
Now the vector v is:
 7 -2  0  0
See Also
class Block
ConstFixedSegmentReturnType<Size>::Type segment ( Index  start) const
inlineinherited

This is the const version of segment<int>(Index).

void swap ( const DenseBase< OtherDerived > &  other,
int  = OtherDerived::ThisConstantIsPrivateInPlainObjectBase 
)
inlineinherited

swaps *this with the expression other.

void swap ( PlainObjectBase< OtherDerived > &  other)
inlineinherited

swaps *this with the matrix or array other.

SegmentReturnType tail ( Index  vecSize)
inlineinherited
Returns
a dynamic-size expression of the last coefficients of *this.

This is only for vectors (either row-vectors or column-vectors), i.e. matrices which are known at compile-time to have either one row or one column.

Parameters
vecSizethe number of coefficients in the block

Example:

RowVector4i v = RowVector4i::Random();
cout << "Here is the vector v:" << endl << v << endl;
cout << "Here is v.tail(2):" << endl << v.tail(2) << endl;
v.tail(2).setZero();
cout << "Now the vector v is:" << endl << v << endl;

Output:

Here is the vector v:
 7 -2  6  6
Here is v.tail(2):
6 6
Now the vector v is:
 7 -2  0  0
Note
Even though the returned expression has dynamic size, in the case when it is applied to a fixed-size vector, it inherits a fixed maximal size, which means that evaluating it does not cause a dynamic memory allocation.
See Also
class Block, block(Index,Index)
ConstSegmentReturnType tail ( Index  vecSize) const
inlineinherited

This is the const version of tail(Index).

FixedSegmentReturnType<Size>::Type tail ( )
inlineinherited
Returns
a fixed-size expression of the last coefficients of *this.

This is only for vectors (either row-vectors or column-vectors), i.e. matrices which are known at compile-time to have either one row or one column.

The template parameter Size is the number of coefficients in the block

Example:

RowVector4i v = RowVector4i::Random();
cout << "Here is the vector v:" << endl << v << endl;
cout << "Here is v.tail(2):" << endl << v.tail<2>() << endl;
v.tail<2>().setZero();
cout << "Now the vector v is:" << endl << v << endl;

Output:

Here is the vector v:
 7 -2  6  6
Here is v.tail(2):
6 6
Now the vector v is:
 7 -2  0  0
See Also
class Block
ConstFixedSegmentReturnType<Size>::Type tail ( ) const
inlineinherited

This is the const version of tail<int>.

Block<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > topLeftCorner ( Index  cRows,
Index  cCols 
)
inlineinherited
Returns
a dynamic-size expression of a top-left corner of *this.
Parameters
cRowsthe number of rows in the corner
cColsthe number of columns in the corner

Example:

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is m.topLeftCorner(2, 2):" << endl;
cout << m.topLeftCorner(2, 2) << endl;
m.topLeftCorner(2, 2).setZero();
cout << "Now the matrix m is:" << endl << m << endl;

Output:

Here is the matrix m:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is m.topLeftCorner(2, 2):
 7  9
-2 -6
Now the matrix m is:
 0  0 -5 -3
 0  0  1  0
 6 -3  0  9
 6  6  3  9
See Also
class Block, block(Index,Index,Index,Index)
const Block<const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > topLeftCorner ( Index  cRows,
Index  cCols 
) const
inlineinherited

This is the const version of topLeftCorner(Index, Index).

Block<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , CRows, CCols> topLeftCorner ( )
inlineinherited
Returns
an expression of a fixed-size top-left corner of *this.

The template parameters CRows and CCols are the number of rows and columns in the corner.

Example:

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is m.topLeftCorner<2,2>():" << endl;
cout << m.topLeftCorner<2,2>() << endl;
m.topLeftCorner<2,2>().setZero();
cout << "Now the matrix m is:" << endl << m << endl;

Output:

Here is the matrix m:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is m.topLeftCorner<2,2>():
 7  9
-2 -6
Now the matrix m is:
 0  0 -5 -3
 0  0  1  0
 6 -3  0  9
 6  6  3  9
See Also
class Block, block(Index,Index,Index,Index)
const Block<const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , CRows, CCols> topLeftCorner ( ) const
inlineinherited

This is the const version of topLeftCorner<int, int>().

Block<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , CRows, CCols> topLeftCorner ( Index  cRows,
Index  cCols 
)
inlineinherited
Returns
an expression of a top-left corner of *this.
Template Parameters
CRowsnumber of rows in corner as specified at compile time
CColsnumber of columns in corner as specified at compile time
Parameters
cRowsnumber of rows in corner as specified at run time
cColsnumber of columns in corner as specified at run time

This function is mainly useful for corners where the number of rows is specified at compile time and the number of columns is specified at run time, or vice versa. The compile-time and run-time information should not contradict. In other words, cRows should equal CRows unless CRows is Dynamic, and the same for the number of columns.

Example:

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is m.topLeftCorner<2,Dynamic>(2,2):" << endl;
cout << m.topLeftCorner<2,Dynamic>(2,2) << endl;
m.topLeftCorner<2,Dynamic>(2,2).setZero();
cout << "Now the matrix m is:" << endl << m << endl;

Output:

Here is the matrix m:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is m.topLeftCorner<2,Dynamic>(2,2):
 7  9
-2 -6
Now the matrix m is:
 0  0 -5 -3
 0  0  1  0
 6 -3  0  9
 6  6  3  9
See Also
class Block
const Block<const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , CRows, CCols> topLeftCorner ( Index  cRows,
Index  cCols 
) const
inlineinherited

This is the const version of topLeftCorner<int, int>(Index, Index).

Block<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > topRightCorner ( Index  cRows,
Index  cCols 
)
inlineinherited
Returns
a dynamic-size expression of a top-right corner of *this.
Parameters
cRowsthe number of rows in the corner
cColsthe number of columns in the corner

Example:

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is m.topRightCorner(2, 2):" << endl;
cout << m.topRightCorner(2, 2) << endl;
m.topRightCorner(2, 2).setZero();
cout << "Now the matrix m is:" << endl << m << endl;

Output:

Here is the matrix m:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is m.topRightCorner(2, 2):
-5 -3
 1  0
Now the matrix m is:
 7  9  0  0
-2 -6  0  0
 6 -3  0  9
 6  6  3  9
See Also
class Block, block(Index,Index,Index,Index)
const Block<const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > topRightCorner ( Index  cRows,
Index  cCols 
) const
inlineinherited

This is the const version of topRightCorner(Index, Index).

Block<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , CRows, CCols> topRightCorner ( )
inlineinherited
Returns
an expression of a fixed-size top-right corner of *this.
Template Parameters
CRowsthe number of rows in the corner
CColsthe number of columns in the corner

Example:

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is m.topRightCorner<2,2>():" << endl;
cout << m.topRightCorner<2,2>() << endl;
m.topRightCorner<2,2>().setZero();
cout << "Now the matrix m is:" << endl << m << endl;

Output:

Here is the matrix m:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is m.topRightCorner<2,2>():
-5 -3
 1  0
Now the matrix m is:
 7  9  0  0
-2 -6  0  0
 6 -3  0  9
 6  6  3  9
See Also
class Block, block<int,int>(Index,Index)
const Block<const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , CRows, CCols> topRightCorner ( ) const
inlineinherited

This is the const version of topRightCorner<int, int>().

Block<Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , CRows, CCols> topRightCorner ( Index  cRows,
Index  cCols 
)
inlineinherited
Returns
an expression of a top-right corner of *this.
Template Parameters
CRowsnumber of rows in corner as specified at compile time
CColsnumber of columns in corner as specified at compile time
Parameters
cRowsnumber of rows in corner as specified at run time
cColsnumber of columns in corner as specified at run time

This function is mainly useful for corners where the number of rows is specified at compile time and the number of columns is specified at run time, or vice versa. The compile-time and run-time information should not contradict. In other words, cRows should equal CRows unless CRows is Dynamic, and the same for the number of columns.

Example:

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is m.topRightCorner<2,Dynamic>(2,2):" << endl;
cout << m.topRightCorner<2,Dynamic>(2,2) << endl;
m.topRightCorner<2,Dynamic>(2,2).setZero();
cout << "Now the matrix m is:" << endl << m << endl;

Output:

Here is the matrix m:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is m.topRightCorner<2,Dynamic>(2,2):
-5 -3
 1  0
Now the matrix m is:
 7  9  0  0
-2 -6  0  0
 6 -3  0  9
 6  6  3  9
See Also
class Block
const Block<const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > , CRows, CCols> topRightCorner ( Index  cRows,
Index  cCols 
) const
inlineinherited

This is the const version of topRightCorner<int, int>(Index, Index).

RowsBlockXpr topRows ( Index  n)
inlineinherited
Returns
a block consisting of the top rows of *this.
Parameters
nthe number of rows in the block

Example:

Array44i a = Array44i::Random();
cout << "Here is the array a:" << endl << a << endl;
cout << "Here is a.topRows(2):" << endl;
cout << a.topRows(2) << endl;
a.topRows(2).setZero();
cout << "Now the array a is:" << endl << a << endl;

Output:

Here is the array a:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is a.topRows(2):
 7  9 -5 -3
-2 -6  1  0
Now the array a is:
 0  0  0  0
 0  0  0  0
 6 -3  0  9
 6  6  3  9
See Also
class Block, block(Index,Index,Index,Index)
ConstRowsBlockXpr topRows ( Index  n) const
inlineinherited

This is the const version of topRows(Index).

NRowsBlockXpr<N>::Type topRows ( )
inlineinherited
Returns
a block consisting of the top rows of *this.
Template Parameters
Nthe number of rows in the block

Example:

Array44i a = Array44i::Random();
cout << "Here is the array a:" << endl << a << endl;
cout << "Here is a.topRows<2>():" << endl;
cout << a.topRows<2>() << endl;
a.topRows<2>().setZero();
cout << "Now the array a is:" << endl << a << endl;

Output:

Here is the array a:
 7  9 -5 -3
-2 -6  1  0
 6 -3  0  9
 6  6  3  9
Here is a.topRows<2>():
 7  9 -5 -3
-2 -6  1  0
Now the array a is:
 0  0  0  0
 0  0  0  0
 6 -3  0  9
 6  6  3  9
See Also
class Block, block(Index,Index,Index,Index)
ConstNRowsBlockXpr<N>::Type topRows ( ) const
inlineinherited

This is the const version of topRows<int>().

const CwiseUnaryOp<CustomUnaryOp, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > unaryExpr ( const CustomUnaryOp &  func = CustomUnaryOp()) const
inlineinherited

Apply a unary operator coefficient-wise.

Parameters
[in]funcFunctor implementing the unary operator
Template Parameters
CustomUnaryOpType of func
Returns
An expression of a custom coefficient-wise unary operator func of *this

The function ptr_fun() from the C++ standard library can be used to make functors out of normal functions.

Example:

#include <Eigen/Core>
#include <iostream>
using namespace Eigen;
using namespace std;
// define function to be applied coefficient-wise
double ramp(double x)
{
if (x > 0)
return x;
else
return 0;
}
int main(int, char**)
{
Matrix4d m1 = Matrix4d::Random();
cout << m1 << endl << "becomes: " << endl << m1.unaryExpr(ptr_fun(ramp)) << endl;
return 0;
}

Output:

   0.68   0.823  -0.444   -0.27
 -0.211  -0.605   0.108  0.0268
  0.566   -0.33 -0.0452   0.904
  0.597   0.536   0.258   0.832
becomes: 
  0.68  0.823      0      0
     0      0  0.108 0.0268
 0.566      0      0  0.904
 0.597  0.536  0.258  0.832

Genuine functors allow for more possibilities, for instance it may contain a state.

Example:

#include <Eigen/Core>
#include <iostream>
using namespace Eigen;
using namespace std;
// define a custom template unary functor
template<typename Scalar>
struct CwiseClampOp {
CwiseClampOp(const Scalar& inf, const Scalar& sup) : m_inf(inf), m_sup(sup) {}
const Scalar operator()(const Scalar& x) const { return x<m_inf ? m_inf : (x>m_sup ? m_sup : x); }
Scalar m_inf, m_sup;
};
int main(int, char**)
{
Matrix4d m1 = Matrix4d::Random();
cout << m1 << endl << "becomes: " << endl << m1.unaryExpr(CwiseClampOp<double>(-0.5,0.5)) << endl;
return 0;
}

Output:

   0.68   0.823  -0.444   -0.27
 -0.211  -0.605   0.108  0.0268
  0.566   -0.33 -0.0452   0.904
  0.597   0.536   0.258   0.832
becomes: 
    0.5     0.5  -0.444   -0.27
 -0.211    -0.5   0.108  0.0268
    0.5   -0.33 -0.0452     0.5
    0.5     0.5   0.258     0.5
See Also
class CwiseUnaryOp, class CwiseBinaryOp
const CwiseUnaryView<CustomViewOp, const Matrix< _Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols > > unaryViewExpr ( const CustomViewOp &  func = CustomViewOp()) const
inlineinherited
Returns
an expression of a custom coefficient-wise unary operator func of *this

The template parameter CustomUnaryOp is the type of the functor of the custom unary operator.

Example:

#include <Eigen/Core>
#include <iostream>
using namespace Eigen;
using namespace std;
// define a custom template unary functor
template<typename Scalar>
struct CwiseClampOp {
CwiseClampOp(const Scalar& inf, const Scalar& sup) : m_inf(inf), m_sup(sup) {}
const Scalar operator()(const Scalar& x) const { return x<m_inf ? m_inf : (x>m_sup ? m_sup : x); }
Scalar m_inf, m_sup;
};
int main(int, char**)
{
Matrix4d m1 = Matrix4d::Random();
cout << m1 << endl << "becomes: " << endl << m1.unaryExpr(CwiseClampOp<double>(-0.5,0.5)) << endl;
return 0;
}

Output:

   0.68   0.823  -0.444   -0.27
 -0.211  -0.605   0.108  0.0268
  0.566   -0.33 -0.0452   0.904
  0.597   0.536   0.258   0.832
becomes: 
    0.5     0.5  -0.444   -0.27
 -0.211    -0.5   0.108  0.0268
    0.5   -0.33 -0.0452     0.5
    0.5     0.5   0.258     0.5
See Also
class CwiseUnaryOp, class CwiseBinaryOp
CoeffReturnType value ( ) const
inlineinherited
Returns
the unique coefficient of a 1x1 expression

The documentation for this class was generated from the following files: