int func_input(double* A, int n){
for (int i = 0; i < n; i++){
for (int j = 0; j < n; j++){
A[i*n + j] = Aij(i,j);
if (fabs(Aij(i,j) - Aij(j,i)) > EPS){
printf("It is not diagonal matrix.\n");
return -1;
}
}
}
return 0;
}
int func_input(double* A, int n){
for (int i = 0; i < n; i++){
for (int j = 0; j < n; j++){
A[i*n+ j] = Aij(i,j);
}
}
return 0;
}
double residual_norm(int n, double *b, double *x){
double m,l = 0.;
for (int i = 0; i < n; i++){
m = 0.;
for (int j = 0; j < n; j++){
m += Aij(i,j)*x[j];
}
m -= b[i];
l += m*m;
}
return sqrt(l);
}
//! Check if block (i,j) is a zero block.
int IsZeroBlock(int i, int j) const {
return (Aij(i,j)==NULL) ? 1 : 0;
}
