VPUBLIC void Vgsrb(int *nx, int *ny, int *nz, int *ipc, double *rpc, double *ac, double *cc, double *fc, double *x, double *w1, double *w2, double *r, int *itmax, int *iters, double *errtol, double *omega, int *iresid, int *iadjoint)
Guass-Seidel solver.