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Convert dolfin::Matrix into Eigen::Matrix

0 votes

Hi !

I have given a dolfin::Matrix M, which I have built through dolfin::assemble. It could be, for example, the mass matrix of a FE discretization.

Now, I would like to convert this matrix M into an Eigen::MatrixXd.

Do you know an efficient way to do this?

I would be very grateful for any help!
Moerni

asked Nov 10, 2015 by Moerni FEniCS Novice (120 points)

1 Answer

0 votes

It should be fairly easy. Try:

parameters['linear_algebra_backend'] = 'Eigen'
M = Matrix()
M0 = as_backend_type(M)
answered Nov 10, 2015 by chris_richardson FEniCS Expert (31,740 points)

Thanks for your quick reply!
I am using C++ ... so do you know how to use "as_backend_type" there?
Thanks in advance!

commented Nov 10, 2015 by Moerni FEniCS Novice (120 points)

You should be able to assemble directly into an EigenMatrix as it inherits from GenericMatrix.

commented Nov 10, 2015 by chris_richardson FEniCS Expert (31,740 points)
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