VEXTERNC void Vmvcs(int *nx, int *ny, int *nz, double *x, int *iz, double *w0, double *w1, double *w2, double *w3, int *istop, int *itmax, int *iters, int *ierror, int *nlev, int *ilev, int *nlev_real, int *mgsolv, int *iok, int *iinfo, double *epsiln, double *errtol, double *omega, int *nu1, int *nu2, int *mgsmoo, int *ipc, double *rpc, double *pc, double *ac, double *cc, double *fc, double *tru)
MG helper functions.