fixsqrt.cpp

来自「这是我本人编写的一个32位定点小数运算的函数库。对于没有浮点运算器的场合」· C++ 代码 · 共 37 行

// FixSqrt.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <stdio.h>
#include <conio.h>
#include <stdlib.h>

#pragma warning(disable:4514)
#include <math.h>

//long FixSqrt32(long x,long y);
extern "C" long FixSqrt32(long x,long y);
extern "C" long FixSqrt32_C(long x,long y);

#define N (1<<26)

int main()
{
	double sum=0,maxd=0;
	for (int i=0;i<10000;i++) {
		double x=(double)(rand()-RAND_MAX/2)/(RAND_MAX/2);
		double y=(double)(rand()-RAND_MAX/2)/(RAND_MAX/2);
		double z=sqrt(x*x+y*y);

		long ix=(long)(x*N+0.5),iy=(long)(y*N+0.5);
		long iz=FixSqrt32_C(ix,iy);
		//long iz=FixSqrt32(ix,iy);
		double d=fabs(z-(double)iz/N);
		sum+=d; if (d>maxd) maxd=d;
	}
	printf("Aver delta=%-20.18lf\tMax Delta=%-20.18lf\n",sum/10000,maxd);
	getch();

	return 0;
}