mtcl.c

来自「数值分析算法描述与习题解答」· C语言 代码 · 共 36 行

  #include "math.h"
  void mtcl(x,b,m,eps,f)
  int m;
  double *x,b,eps,(*f)();
  { double rnd1();
    int k;
    double xx,a,r,y,x1,y1;
    a=b; k=1; r=1.0; xx=*x; y=(*f)(xx);
    while (a>=eps)
      { x1=rnd1(&r); x1=-a+2.0*a*x1;
        x1=xx+x1; y1=(*f)(x1);
        k=k+1;
        if (fabs(y1)>=fabs(y))
          { if (k>m) { k=1; a=a/2.0; }}
        else
          { k=1; xx=x1; y=y1;
            if (fabs(y)<eps)
              { *x=xx; return; }
          }
      }
    *x=xx; return;
  }

  static double rnd1(r)
  double *r;
  { int m;
    double s,u,v,p;
    s=65536.0; u=2053.0; v=13849.0;
    m=(int)(*r/s); *r=*r-m*s;
    *r=u*(*r)+v; m=(int)(*r/s);
    *r=*r-m*s; p=*r/s;
    return(p);
  }