7.8 求解非线性方程组一组实根的梯度法 snse.c

许士良常用算法程序集C语言,包括c++一些常用算法代码

#include "stdlib.h"
#include "math.h"
int snse(n,eps,x,js,ff)
int n,js;
double eps,x[],(*ff)();
{ 
	int l,j;
    double f,d,s,*y;
    y=malloc(n*sizeof(double));
    l=js;
    f=(*ff)(x,y,n);
    while (f>=eps)
    { 
		l=l-1;
        if (l==0) 
		{ 
			free(y); 
			return(js);
		}
        d=0.0;
        for (j=0; j<=n-1; j++) d=d+y[j]*y[j];
        if (d+1.0==1.0) 
		{ 
			free(y); 
			return(-1);
		}
        s=f/d;
        for (j=0; j<=n-1; j++) x[j]=x[j]-s*y[j];
        f=(*ff)(x,y,n);
    }
    free(y); 
	return(js-l);
}