c语言牛顿迭代法求平方根的过程如下:

牛顿迭代法开方的过程如下:
(1)设置初始值为1
(2)如果|猜测值*猜测值-X|(3)设置新猜测值为(x/猜测值+猜测值)/2,返回(2)
(4)猜测值就是满足要求的x的平方根

#include

float sqrt(float);
float fabs(float);
void main()
{
 float FloatNum;

 clrscr();
 printf("Please enter a float number:");
 scanf("%f",&FloatNum);
 printf("Square_root of (fabs(%f)) = %f/n",FloatNum,sqrt(FloatNum));
}
/*牛顿迭代法求实数x的平方根*/
float sqrt(float x)
{
 float EpsilonNum,GuessNum;
 EpsilonNum = 1E-5;
 GuessNum = 1.0;
 while( fabs(GuessNum*GuessNum - fabs(x)) >= EpsilonNum )
 {
  GuessNum = (fabs(x)/GuessNum + GuessNum) / 2.0;
 }
 return(GuessNum);
}

/*求x的绝对值*/
float fabs(float x)
{
 if( x < 0 )
 {
  x = -x;
 }
 return(x);
}