7.9 求解非线性方程组一组实根的拟牛顿法 netn.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"
#include "stdio.h"
#include "6gaus.c"
int netn(n,eps,t,h,x,k,f)
int n,k;
void (*f)();
double eps,t,h,x[];
{ 
	int i,j,l;
    double am,z,beta,d,*y,*a,*b;
    y=malloc(n*sizeof(double));
    a=malloc(n*n*sizeof(double));
    b=malloc(n*sizeof(double));
    l=k; am=1.0+eps;
    while (am>=eps)
    { 
		(*f)(x,b,n);
        am=0.0;
        for (i=0; i<=n-1; i++)
        { 
			z=fabs(b[i]);
            if (z>am) am=z;
        }
        if (am>=eps)
        { 
			l=l-1;
            if (l==0)
            { 
				free(y); free(b); free(a);
                printf("fail\n"); 
				return(0);
            }
            for (j=0; j<=n-1; j++)
            { 
				z=x[j]; x[j]=x[j]+h;
                (*f)(x,y,n);
                for (i=0; i<=n-1; i++) a[i*n+j]=y[i];
                x[j]=z;
            }
            if (gaus(a,b,n)==0)
            { 
				free(y); free(a); free(b); 
				return(-1);
			}
            beta=1.0;
            for (i=0; i<=n-1; i++) beta=beta-b[i];
            if (fabs(beta)+1.0==1.0)
            { 
				free(y); free(a); free(b);
                printf("fail\n"); 
				return(-2);
            }
            d=h/beta;
            for (i=0; i<=n-1; i++) x[i]=x[i]-d*b[i];
            h=t*h;
        }
    }
    free(y); free(a); free(b);
    return(k-l);
}