# Matrix Inversion no solver

Hello everyone,

I want to solve a linear system. I have a vandermonde matrix in a linear system. I figured out i should solve it with `real[int] sol = A^-1 * b` as suggested in the documentation, but i get the following error :

``````MATERROR 1 : VirtualMatrix:: no solver ?????
current line = 90
call interpolation  at  line 95
Exec error : MATERROR
-- number :1
Exec error : MATERROR
-- number :1
err code 8 ,  mpirank 0
``````

Why do i have to specify a solver, i thought this is regular matrix inversion (gauss-jordan?). How should i specify the solver ?

Here is the code :

``````func real[int] interpolation(real[int] A, real[int] B, real pente) {
matrix vandermonde =
[[A  ^ 3, A  ^ 2, A , 1], [B  ^ 3, B  ^ 2, B , 1],
[3 * A  ^ 2, 2 * A , 1, 0], [3 * B  ^ 2, 2 * B , 1, 0]];
real[int] sndmembre = [ A, B, 0, pente ];
real[int] sol = vandermonde ^ -1 * sndmembre;
return sol;
}

real[int] p10 = p1 + departChauffe;
real[int] coeffs = interpolation(p1, p10, pente);
``````

Thank you for your help What if you do `set(vandermonde, solver = sparse solver);` before the call to `^-1`?

1 Like

it worked, i used `sparsesolver` in one word, thank you Sorry for the small error on behalf of my auto-correct.