Hi Everyone,

I'm new to Eigen and I'm trying to implement a simple PDE solver for the 1D heat equation.

I defined A a matrix

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Eigen::internal::TridiagonalMatrix<double,N,0> A;

and P a vector

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MatrixXd P=MatrixXd::Constant(N,1,0);

And the compiler won't compile the product of the Tridiagonal Matrix and the vector... (no match for operator * in 'A*P')

What am I doing wrong?

Thanks for your help!

TridiagonalMatrix is an internal class, it is not meant to be used by users since currently it only supports storage.

Thanks!

What's the usual solution for people doing PDEs (or any task where tridiagonal matrix are present) then? Just use sparse matrix instead? This would work but we would lose some speed...

In the meantime you can directly call BLAS/Lapack routines.