root.c

徐士良写的《数值分析与算法》

    #include "stdio.h"
    #include "math.h"
    double  root(a,b,eps,f)
    double  a,b,eps,(*f)();
    { double  f0,f1,c;
      f0=(*f)(a);
      while (fabs(a-b)>=eps)
        { c=(a+b)/2; f1=(*f)(c);
          if (f1==0)  return(c);
          if (f0*f1>0)  a=c;
          else  b=c;
        }
      c=(a+b)/2;
      return(c);
    }