# Bessel Functions

Visual Studio 6.0

The Bessel functions are commonly used in the mathematics of electromagnetic wave theory.

These routines return Bessel functions of the first kind: orders 0, 1, and n, respectively.

These routines return Bessel functions of the second kind: orders 0, 1, and n, respectively.

Example

``````/* BESSEL.C: This program illustrates Bessel functions,
* including:    _j0   _j1   _jn   _y0   _y1   _yn
*/

#include <math.h>
#include <stdio.h>

void main( void )
{
double x = 2.387;
int n = 3, c;

printf( "Bessel functions for x = %f:\n", x );
printf( " Kind\t\tOrder\tFunction\tResult\n\n" );
printf( " First\t\t0\t_j0( x )\t%f\n", _j0( x ) );
printf( " First\t\t1\t_j1( x )\t%f\n", _j1( x ) );
for( c = 2; c < 5; c++ )
printf( " First\t\t%d\t_jn( n, x )\t%f\n", c, _jn( c, x ) );
printf( " Second\t0\t_y0( x )\t%f\n", _y0( x ) );
printf( " Second\t1\t_y1( x )\t%f\n", _y1( x ) );
for( c = 2; c < 5; c++ )
printf( " Second\t%d\t_yn( n, x )\t%f\n", c, _yn( c, x ) );
}

``````

Output

``````Bessel functions for x = 2.387000:
Kind      Order   Function   Result

First      0   _j0( x )   0.009288
First      1   _j1( x )   0.522941
First      2   _jn( n, x )   0.428870
First      3   _jn( n, x )   0.195734
First      4   _jn( n, x )   0.063131
Second   0   _y0( x )   0.511681
Second   1   _y1( x )   0.094374
Second   2   _yn( n, x )   -0.432608
Second   3   _yn( n, x )   -0.819314
Second   4   _yn( n, x )   -1.626833

``````

See Also   _matherr

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