2fenfa.c

来自「C语言程 反对萨芬记录卡上的交付离开的撒娇发了啊」· C语言 代码 · 共 34 行

/*用对分法求x*x*x-2*x*x-4*x-7=0在3到4的根*/
#define EPS 5e-3
#define DELTA 1e-6
#include"conio.h"
#include"stdio.h"
#include"math.h"
float Bisection(float,float,float(*f)(float));
float f(float) ;
main()
{   float a=3,b=4;
    float x;
    x=Bisection(a,b,f);
printf("\nThe root of the equation is %f",x);
     getch();
 }
  float Bisection(float a,float b,float(*f)(float))
       { float c,fc,fa=f(a),fb=f(b) ;
          int n=1;
              printf("c\t\tf(c)\n") ;
              while(1)
              { if(fa*fb>0) exit();
                c=(a+b)/2,fc=f(c);
                 if(fabs(fc)<DELTA) break ;
                 else if(fa*fc<0) {b=c;fb=fc;}
                      else {a=c;fa=fc;}
                      if(b-a<EPS) break;
                printf("%d\t\t%f\n",n++,c,fc) ; }
           return c;
        }
           float f(float x)
           {
           return x*x*x-2*x*x-4*x-7;
           }