On 10/10/2016 09:52 AM, Edith Sotelo wrote:
It works with a direct solver.
It is working with the CG solver as well I just increased the number of
iterations (1000-> 2000) and decreased the tolerance (10^ -12 -> 10 ^ -10)
Note about the system I am solving:
In my PDE my RHS =0 (homogenous Helmholtz Eq. with Dirichlet BC) , Basically
I am solving a system Ax=0
If there is a better way to solve this I would like to try.
I think it's not quite clear to me what you do. If you solve the equation
operator * u = 0
but with nonzero Dirichlet boundary condition, then this leads to a linear
system
A x = b
where b is not the zero vector. That's because the boundary values appear in
the rhs vector. You need to solve this like any other linear system.
However, if you have the Helmholtz equation with the "bad" sign in front of
the mass term, then the matrix may be indefinite, and CG can not solve it.
Best
W.
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Wolfgang Bangerth email: [email protected]
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