d4r27.cpp

此代码为VC++常用数值算法这本书中附赠的光D部分的源代码

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

void main()
{
    //program d4r27
    //driver for routine besian
    int i,n[19];
	char text[20];
    double nval,a[19],value[19],x[19],f[19],temp,ih; 
    const double pi = 3.1415926;
	temp=3;
    fstream fin;
    fin.open("d:\\vc常用数值算法集\\data\\fncval.dat",ios::in);
    while ( strcmp(text,"Ia+n")!=0 )
	{
      fin>>text;
	}
    fin>>nval; 
    fin>>text;
	cout<<"Modified Bessel Function Ia+n "<<endl;
    cout<<endl;
    cout<<"  n    a    ih    x     actual      besian"<<endl;
    for (i = 0 ; i<=nval - 1; i++)
	{
        fin>>n[i];
        fin>>a[i];
        fin>>x[i];
        fin>>value[i];
    }
    ih = 1;
    besian(x[0], a[0], temp, ih, f);
    for( i = 0;i<=3;i++)
	{
		cout<<setw(6)<<n[i];
        cout<<setw(6)<<a[i];
		cout<<setw(6)<<ih;
		cout<<setw(6)<<x[i];
		cout<<setw(16)<<value[i];
		cout<<setw(16)<<f[i]<<endl;
	}
    besian(x[4], a[4], temp, ih, f);
    for( i = 4;i<=7;i++)
	{
		cout<<setw(6)<<n[i];
        cout<<setw(6)<<a[i];
		cout<<setw(6)<<ih;
		cout<<setw(6)<<x[i];
		cout<<setw(16)<<value[i];
		cout<<setw(16)<<f[i-4]<<endl;
    }
    ih = -1;
    besian(x[8], a[8], temp, ih, f);
    for( i = 8;i<=10;i++)
	{
		cout<<setw(6)<<n[i];
        cout<<setw(6)<<a[i];
		cout<<setw(6)<<ih;
		cout<<setw(6)<<x[i];
		cout<<setw(16)<<value[i];
		cout<<setw(16)<<f[i-7]<<endl;
    }
    besian(x[11], a[11], temp, ih, f);
    for( i = 11;i<=13;i++)
	{
		cout<<setw(6)<<n[i];
        cout<<setw(6)<<a[i];
		cout<<setw(6)<<ih;
		cout<<setw(6)<<x[i];
		cout<<setw(16)<<value[i];
		cout<<setw(16)<<f[i-10]<<endl;
    }
}