C++全主元高斯消元法解线性方程组（徐士良）

#include<stdio.h>
#include<math.h>
#include<stdlib.h>
int gsdl(a, b, n, x, eps);
int n;
double a[], b[], x[], eps;
	{
	int i, j, u, v;
	double p, t, s, q;
	for (i = 0; i <= n - 1; i++) {
		u = i * n + i; p = 0.0; x[i] = 0.0;
		for (j = 0; j <= n - 1; j++) {
			if (i != j) { v = i * n + j; p = p + fabs(a[v]); }
			if (p >= fabs(a[u])) { printf("fail\n"); return 0; }
		}
	}
	p = eps + 1.0;
	while (p >= eps)
	{
		p = 0.0;
		for (i = 0; i <= n - 1; i++)
		{
			t = x[i]; s = 0.0;
			for (j = 0; j < n - 1; j++)
				if (j != i) s = s + a[i * n + j] * x[j];
			x[i] = (b[i] - s) / a[i * n + i];
			q = fabs(x[i] - t) / (1.0 + fabs(x[i]));
			if (q > p)  p = q; 
		}
	}
	return(1);
}