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<title>An Example Program - GNU Scientific Library -- Reference Manual</title>
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<h3 class="section">2.1 An Example Program</h3>
<p>The following short program demonstrates the use of the library by
computing the value of the Bessel function J_0(x) for x=5,
<pre class="example"><pre class="verbatim"> #include <stdio.h>
#include <gsl/gsl_sf_bessel.h>
int
main (void)
{
double x = 5.0;
double y = gsl_sf_bessel_J0 (x);
printf ("J0(%g) = %.18e\n", x, y);
return 0;
}
</pre></pre>
<p class="noindent">The output is shown below, and should be correct to double-precision
accuracy,
<pre class="example"><pre class="verbatim"> J0(5) = -1.775967713143382920e-01
</pre></pre>
<p class="noindent">The steps needed to compile this program are described in the following
sections.
<hr>The GNU Scientific Library - a free numerical library licensed under the GNU GPL<br>Back to the <a href="/software/gsl/">GNU Scientific Library Homepage</a></body></html>
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