如何访问第三方源文件中的功能？

Question

I was looking for an algorithm that would enable me to use the mathematical Bessel function for complex numbers. Now I have found a promising result . (I'm interested in Bessel functions Jv and Yv for real or complex arguments and real order .)

I am working in Visual Studio 2010 Express C++ and now I want to get access to those functions implemented there. How do I do that?

Answer 1

Download this http://www.crbond.com/download/bessel.zip file and add the files to your visual studio project. To use the functions, you will need to #include "BESSEL.h" to your source file.

I got it compile on Visual Studio by doing the following

1. Adding _USE_MATH_DEFINES to preprocessor definitions.
2. Changing #include <complex.h> to #include <complex>
3. Adding using namespace std; to BESSEL.H

Example of how to call a function:

#include "BESSEL.H"
#include <iostream>

int main() {
    double x, i0, i1, k0, k1, i0p, i1p, k0p, k1p;
    x = 5.0;
    i0 = 1.0;
    i1 = 2.0;
    k0 = 3.0;
    k1 = 4.0;
    i0p = 5.0;
    i1p = 6.0;
    k0p = 7.0;
    k1p = 8.0;

    bessik01a(x, i0, i1, k0, k1, i0p, i1p, k0p, k1p);
    // Results are stored in the variables i0..k1p
    cout << i0 << " " << i1 << " " << k0 << " " << k1;
    return 0;
}

Answer 2

Add the files linked above to your project:

Note you have to edit out old header files in these .cpp files and .h file. More specific: change

#include<complex.h>

to

#include<complex>

and use namespace std. Also for math.h . In main.cpp as in picture above write:

#include <iostream>
using namespace std;

#include "BESSEL.H"

int main ()
{
    complex<double> z = 3;
    complex<double>  J0;
    complex<double>  J1;
    complex<double>  Y0;
    complex<double>  Y1;
    complex<double> J0p;
    complex<double> J1p;
    complex<double> Y0p;
    complex<double> Y1p;

    cbessjy01(z,J0,J1,Y0,Y1,J0p,J1p,Y0p,Y1p);

    cout<< "J0:  " << J0  << "\n";
    cout<< "J0p: " << J0p << "\n";
    cout<< "J1:  " << J1  << "\n";
    cout<< "J1p: " << J1p << "\n";
    cout<< "Y0:  " << Y0  << "\n";
    cout<< "Y0p: " << Y0p << "\n";
    cout<< "Y1:  " << Y1  << "\n";
    cout<< "Y1p: " << Y1p << "\n";

    cin.get();
    return 0;
}

Try to run the program. z is the argument for the bessel function.

You may ask what are J0 , J1 , etc they are the Bessel functions but if you need to detremine which is which try a numerical value in the formulas you have. for example check J0 is the result of which formula. I'm not an expert in Bessel functions. But if you give me the exact formulas you need to use I can test.