shitanfa.c

来自「黄金分割法 C语言 很不错的哦 大家看看」· C语言 代码 · 共 75 行

/* Note:Your choice is C IDE */
#include "stdio.h"
double f(double t)
{
  double f;
  f=t*t-10*t+36;
  return f;
}
main()
{ 
  double e=0.0001,l=0.618;
  double a1,a2,y1,y2,m,n,ap,yp;
  int h0,h;
  double a,c,b,p1,p2,p3;
  h0=3;
  h=h0;
  a=0;
  p1=f(a);
  c=h;
  p2=f(c);
  if(p2>p1)
   {
     h=-h;
     b=a;
     p3=p1;
     a=c;
     p1=p2;
     c=b;
     p2=p3;
   }
  b=c+h;
  p3=f(b);
  while(p3<p2)
  {
    h=2*h;
    a=c;
    p1=p2;
    c=b;
    p2=p3;
  }
  printf("The searching region is:\n");
  printf("[%f,%f]\n",a,b);
  a1=b-l*(b-a);
  y1=f(a1);
  a2=a+l*(b-a); 
  y2=f(a2);
  
  do
   {
      if(y1>=y2)
        {
          a=a1;
          a1=a2;
          y1=y2;
          a2=a+l*(b-a);
          y2=f(a2);
          m=(b-a)/b;
          n=(y2-y1)/y2;
        }
       else
        {
          b=a2;
          a2=a1;
          y2=y1;
          a1=b-l*(b-a);
          y1=f(a1);
          m=(b-a)/b;
          n=(y2-y1)/y2;
        }
    }while((m<-e||m>e)||(n<-e||n>e));
  ap=0.5*(a+b);
  yp=f(ap);
  printf("The result is:\n");
  printf("ap=%f\nyp=%f\n",ap,yp);
}