7snse.c

《C常用算法程序集 第三版》源代码

  #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);
  }