static void
icgsm(double *u, double *unrm, int n, int m, double *Q,
PyObject *mmat,
double *um, double *temp) {
const int maxcgsit = 5;
const double alpha = 0.5;
double unrm_old;
int ret, i, isorth = 0;
ret = SpMatrix_Matvec(mmat, n, u, n, um);
assert(ret == 0);
*unrm = sqrt(F77(ddot)(&n, u, &ONE, um, &ONE));
if (m == 0)
return;
for (i = 0; !isorth && i < maxcgsit; i ++) {
F77(dgemv)("t", &n, &m, &DONE, Q, &n, um, &ONE, &DZER, temp, &ONE, 1);
F77(dgemv)("n", &n, &m, &DMONE, Q, &n, temp, &ONE, &DONE, u, &ONE, 1);
ret = SpMatrix_Matvec(mmat, n, u, n, um);
assert(ret == 0);
unrm_old = (*unrm);
*unrm = sqrt(F77(ddot)(&n, u, &ONE, um, &ONE));
isorth=((*unrm) > alpha*unrm_old);
}
if (i >= maxcgsit) {
printf("warning: loss of orthogonality. ");
printf("icgsm() not converged after %d steps.\n", maxcgsit);
}
}
static int
jacobi(PyObject *matrix, int n, double *dinv, int steps, double *x, double *y, double *temp) {
int ONE = 1;
int i, step, res;
/* 1st step */
for (i = 0; i < n; i ++)
y[i] = x[i]*dinv[i];
/* following steps */
for(step = 1; step < steps; step ++) {
F77(dcopy)(&n, y, &ONE, temp, &ONE);
res = SpMatrix_Matvec(matrix, n, temp, n, y);
if (res == -1)
return res;
for (i = 0; i < n; i ++)
y[i] = (x[i] - y[i])*dinv[i] + temp[i];
}
return 0;
}
