牛顿迭代法求根

 #include <stdio.h>
 #include <math.h>

 float solut(float a, float b, float c, float d)
 {
     float x = 1, x0, f, f1;

     do//开始迭代
     {
         x0 = x;
         f = ((a * x0 + b) * x0 + c) * x0 + d;
         f1 = (3 * a * x0 + 2 * b) * x0 + c;
         x = x0 - f / f1;
     }
     while (fabs(x - x0) >= 1e-5);

     return x;
 }

 int main()
 {
     float a, b, c, d;

     printf("\n输入方程的系数a、b、c、d：\n");
     scanf("%f,%f,%f,%f", &a, &b, &c, &d);
     printf("\n方程是：%5.2fx^3+%5.2fx^2+%5.2fx+%5.2f=0", a, b, c, d);
     printf("\nX=%10.7f\n", solut(a, b, c, d));

     return 0;
 }