golden.h

优化设计常用程序

float f(float);
#define r 0.618
float  golden(double a,double b,float E)
{
  float y1,y2,a1,a2;
  a1=b-r*(b-a);
  a2=a+r*(b-a);
  y1=f(a1);
  y2=f(a2);
  do
    { /* printf("\na=%f,a1=%f,a2=%f,b=%f,y1=%f,y2=%f",a,a1,a2,b,y1,y2);
      getch(); */
      if(y1>=y2)
	{
	  a=a1;
	  a1=a2;
	  y1=y2;
	  a2=a+r*(b-a);
	  y2=f(a2);
	}
      else
	{
	  b=a2;
	  a2=a1;
	  y2=y1;
	  a1=b-r*(b-a);
	  y1=f(a1);
	}
    }while(fabs((b-a)/b)>=E&&fabs((y2-y1)/y2)>=E);
  printf("\nThe result  a is:%f", (a+b)/2.);
  getch();
  return((a+b)/2.);
}