牛顿迭代法求平方根

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|<E ,转到(4)

(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 <stdio.h>

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);

}