Solve Ad * x = b for the preconditioner matrix Ad.
Method Detail
solve
void solve(double[] b,
double[] x)
Solve Ad * x = b for the preconditioner matrix Ad.
The preconditioner matrix Ad is close to A and should be
easy to solve for linear systems. This method is useful for preconditioned
conjugate gradient method. The preconditioner matrix could be as simple
as the trivial diagonal part of A in some cases.