Hi!

I need an advise how to deal with a large matrices. Now I try to find a product of two matrices with this code:

#include
#include

USING_PART_OF_NAMESPACE_EIGEN

#define dim 1024

int main(int, char *[])
{
Matrix A;
Matrix B;
Matrix C;

srand(2006);
A.setRandom();
B.setRandom();

C = A * B;

}

And I can't even compile it with mingw gcc-4.3 and a lot of errors like
"
eigen-2.0.0/Eigen/src/Core/Assign.h: In instantiation of 'Eigen::ei_assign_traits, Eigen::Product&, const Eigen::Matrix&, 0> >':
eigen-2.0.0/Eigen/src/Core/Assign.h:407: instantiated from 'Derived& Eigen::MatrixBase::lazyAssign(const Eigen::MatrixBase&) [with OtherDerived = Eigen::Product&, const Eigen::Matrix&, 0>, Derived = Eigen::Matrix]'
eigen-2.0.0/Eigen/src/Core/Assign.h:422: instantiated from 'static Derived& Eigen::ei_assign_selector::run(Derived&, const OtherDerived&) [with Derived = Eigen::Matrix, OtherDerived = Eigen::Product&, const Eigen::Matrix&, 0>]'
eigen-2.0.0/Eigen/src/Core/Matrix.h:508: instantiated from 'Eigen::Matrix& Eigen::Matrix::_set_noalias(const Eigen::MatrixBase&) [with OtherDerived = Eigen::Product&, const Eigen::Matrix&, 0>, _Scalar = float, int _Rows = 1024, int _Cols = 1024, int _Options = 2, int _MaxRows = 1024, int _MaxCols = 1024]'
eigen-2.0.0/Eigen/src/Core/Matrix.h:385: instantiated from 'Eigen::Matrix::Matrix(const Eigen::MatrixBase&) [with OtherDerived = Eigen::Product&, const Eigen::Matrix&, 0>, _Scalar = float, int _Rows = 1024, int _Cols = 1024, int _Options = 2, int _MaxRows = 1024, int _MaxCols = 1024]'
eigen-2.0.0/Eigen/src/Core/MatrixBase.h:497: instantiated from 'const typename Eigen::ei_eval::type Eigen::MatrixBase::eval() const [with Derived = Eigen::Product&, const Eigen::Matrix&, 0>]'
eigen-2.0.0/Eigen/src/Core/Assign.h:426: instantiated from 'static Derived& Eigen::ei_assign_selector::run(Derived&, const OtherDerived&) [with Derived = Eigen::Matrix, OtherDerived = Eigen::Product&, const Eigen::Matrix&, 0>]'
eigen-2.0.0/Eigen/src/Core/Assign.h:442: instantiated from 'Derived& Eigen::MatrixBase::operator=(const Eigen::MatrixBase&) [with OtherDerived = Eigen::Product&, const Eigen::Matrix&, 0>, Derived = Eigen::Matrix]'
eigen-2.0.0/Eigen/src/Core/Matrix.h:494: instantiated from 'Eigen::Matrix& Eigen::Matrix::_set(const Eigen::MatrixBase&) [with OtherDerived = Eigen::Product&, const Eigen::Matrix&, 0>, _Scalar = float, int _Rows = 1024, int _Cols = 1024, int _Options = 2, int _MaxRows = 1024, int _MaxCols = 1024]'
eigen-2.0.0/Eigen/src/Core/Matrix.h:263: instantiated from 'Eigen::Matrix& Eigen::Matrix::operator=(const Eigen::MatrixBase&) [with OtherDerived = Eigen::Product&, const Eigen::Matrix&, 0>, _Scalar = float, int _Rows = 1024, int _Cols = 1024, int _Options = 2, int _MaxRows = 1024, int _MaxCols = 1024]'
egn2mmul.cpp:24: instantiated from here
"

are showed.

When I reduce dimension, all works.

What I do wrong?

You are trying to use fixed-size 1024x1024. That's very unlikely to work: for such large sizes, you should use dynamic-size instead. So the matrix type you're looking for is MatrixXf, which is a typedef for Matrix. You should use that instead of Matrix.

Code: Select all

MatrixXf m(dim, dim);


Thanks a lot!

It works!