I actually did this. Not by checking the norm but saving the matrix and
rhs to a file. There are no nan or inf values.
As I can solve the eqns exactly in 1d I built a vector with the exact
solution and tested if it's a solution of the computed system.
dealii::VectorTools::interpolate(dofHandler, ExSolutionFunction<1>(),
exSolution);
dealii::Vector<double> mult(rhs.size());
systemMatrix.vmult(mult, exSolution);
std::cout << mult-rhs << std::endl;
Not very surprisingly, it's not. It seems to be working for one of the
components (the scalar one) of the FESystem but not for the other one.
I again checked the assembling of the matrix and rhs but couldn't find
any mistake.
Wolfgang Bangerth wrote:
"Exception on processing:
Iterative method reported convergence failure in step 1 with residual nan"
I haven't looked at your code, but it strikes me that you get a NaN after only
one iteration. Have you done something like
std::cout << system_matrix.frobenius_norm() << " "
<< system_rhs.l2_norm();
to verify that your matrix/rhs aren't already containing NaNs before you even
hand them over to the solver?
Best
W.
-------------------------------------------------------------------------
Wolfgang Bangerth email: [email protected]
www: http://www.math.tamu.edu/~bangerth/
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