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/**
* test_pcg.c
* ----------
*
* purpose: test solver.pcg()-method
* cf. https://en.wikipedia.org/wiki/Conjugate_gradient_method
* for the test case used
**/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "global.h"
#include "linalg.h"
#include "solver.h"
int main (void)
{
// init system
double a[6] = { 0.0, 1.0, 4.0, 3.0, 1.0, 0.0 };
int ids[3] = { -1, 0, 1 };
struct diag m = { a, ids, 2, 2, 2, 3 };
double c[2] = { 1.0 / 4.0, 1.0 / 3.0 };
int cids[1] = { 0 };
struct diag pre = { c, cids, 2, 2, 2, 1 }; // Jacobi preconditioner
double b[3] = { 1.0, 2.0 };
double x0[2] = { 20000.0, 10000.0 };
pcg(&m, b, x0, &pre, 1.0e-12);
printf(">>> x0: \n");
for (int i = 0; i < 2; i ++) {
printf(">>> %g\n", x0[i]);
}
if (fabs(x0[0] - (1.0/11.0)) <= 1.0e-10) {
printf(">>> test passed.\n");
} else {
printf(">>> test failed. expected: %g, found: %g\n", (1.0/11.0), x0[0]);
}
if (fabs(x0[1] - (7.0/11.0)) <= 1.0e-10) {
printf(">>> test passed.\n");
} else {
printf(">>> test failed. expected: %g, found: %g\n", (7.0/11.0), x0[1]);
}
}
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