d4r5.cpp

数值计算c++源代码,包括各种算法。很有用的。

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

double gammln(double xx)
{
	int j;
	float temp;
    double cof[6],stp,half,one,fpf,x,tmp,ser;
    cof[1] = 76.18009173;
    cof[2] = -86.50532033;
    cof[3] = 24.01409822;
    cof[4] = -1.231739516;
    cof[5] = 0.00120858003;
    cof[6] = -0.00000536382;
    stp = 2.50662827465;
    half = 0.5;
    one = 1.0;
    fpf = 5.5;
    x = xx - one;
    tmp = x + fpf;
    tmp = (x + half) * log(tmp) - tmp;
    ser = one;
    for (j = 1;j<=6;j++)
	{
        x = x + one;
        ser = ser + cof[j] / x;
    }
    temp = tmp + log(stp * ser);
	return temp;
}

double beta(double z, double w)
{
	double temp;
    temp = exp(gammln(z) + gammln(w) - gammln(z + w));
	return temp;
}

void main()
{
    //program d4r5
    //driver for routine Beta
    int i;
	char text[20];
    double w,z,value,nval; 
    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,"Beta")!=0)
	{
      fin>>text;
	}
	fin>>text;
    fin>>nval; 
    cout<<"Beta Function"<<endl;
    fin>>text;
    cout<<endl;
    cout<<"    w       z        Actual        beta(w,z)"<<endl;
    for( i = 1;i<=nval;i++)
	{
        fin>>w;
		fin>>z;
		fin>>value;           
		cout<<setw(5)<<w;
		cout<<setw(8)<<z;
		cout<<setw(16)<<value;
		cout<<setw(16)<<beta(w,z)<<endl;			         
    }
}