//scalar products of vectors
static void vector_scalar_product_TwoVectorsWithCoordinatesFourAndFive_IntegerFourtyOne(void ** state){
vector_t * vec1 = vector_test(4,5);
vector_t * vec2 = vector_test(4,5);
assert_int_equal(vector_scalar_product(vec1,vec2),41);
vector_free(vec1);
vector_findLength(vec2);
}
/*solution saved in b */
void conjugate_gradient(sparse_matrix A, double *b, int size) {
double *x, *r, *p, *Ap, *aux, rnew, rold, alfa;
int i;
x = (double*) malloc(size*sizeof(double));
r = (double*) malloc(size*sizeof(double));
p = (double*) malloc(size*sizeof(double));
Ap = (double*) malloc(size*sizeof(double));
aux = (double*) malloc(size*sizeof(double));
for (i = 0; i < size; i ++) {
x[i] = 0;
r[i] = b[i];
p[i] = b[i];
}
rold = inner_product(r, r, size);
/* result of operations from all void functions used here are stored in the last argument */
while (1) {
matrix_vector_product(A, p, Ap);
alfa = rold / inner_product(p, Ap, size); /*step length*/
vector_scalar_product(p, alfa, size, aux);
vector_sum(x, aux, size, x);
vector_scalar_product(Ap, alfa, size, aux);
vector_subtraction(r, aux, size, r);
rnew = inner_product(r, r, size);
if (sqrt(rnew) < E)
break;
vector_scalar_product(p, rnew / rold, size, p);
vector_sum(p, r, size, p);
rold = rnew;
}
for (i = 0; i < size; i ++) {
b[i] = x[i];
}
free(x);
free(r);
free(p);
free(Ap);
free(aux);
}
