d4r12.cpp

Visual C++ 常用数值算法集 源代码

#include <iostream.h>
#include <math.h>
#include <iomanip.h>
#include <stdlib.h>
#include <fstream.h>
#include <string>
#include <process.h>

double erfcc(double x)
{
	double z,t,ddd,aaa,bbb,ccc,temp;
    z = fabs(x);
    t = 1.0 / (1.0 + 0.5 * z);
    ddd = -0.82215223 + t * 0.17087277;
    aaa = t * (-1.13520398 + t * (1.48851587 + t * ddd));
    bbb = t * (-0.18628806 + t * (0.27886807 + aaa));
    ccc = t * (0.37409196 + t * (0.09678418 + bbb));
    temp= t * exp(-z * z - 1.26551223 + t * (1.00002368 + ccc));
    if (x < 0.0) 
		temp= 2.0 - temp;
	return temp;
}

void main()
{
    //program d4r12
    //driver for routine erfcc
    int i;
	char text[20];
    double nval,actual,x; 
    const double pi = 3.1415926;
    fstream fin;
    fin.open("d:\\vc常用数值算法集\\data\\fncval.dat",ios::in);
    while (strcmp(text,"Error")!=0)
	{
      fin>>text;
	}
	fin>>text;
    fin>>nval; 
    cout<<"Complementary Error Function "<<endl;
    fin>>text;
    cout<<endl;
    cout<<"    x          actual         erfcc(x)"<<endl;
    for( i = 1;i<=nval;i++)
	{
        fin>>x;
		fin>>actual; 
		actual=1-actual;
		cout<<setw(6)<<x;
		cout<<setw(16)<<actual;
		cout<<setw(16)<<erfcc(x)<<endl;			          
    }
}