d4r22.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 d4r22
    //driver for routine bessi1
    int i;
	char text[20];
    double nval,value,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,"I1")!=0) 
	{
      fin>>text;
	}
    fin>>nval; 
    fin>>text;
    cout<<"Modified Bessel Function I1 "<<endl;
    cout<<endl;
    cout<<"     x         actual        bessi1(x)"<<endl;
    for( i = 1;i<=nval;i++)
	{
        fin>>x;
		fin>>value;           
		cout<<setprecision(2)<<setw(6)<<x;
        cout<<setprecision(7)<<setw(16)<<value;
		cout<<setprecision(7)<<setw(16)<<bessi1(x)<<endl;			          
    }
}