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<a name="Auxiliary-random-number-generator-functions"></a>
<div class="header">
<p>
Next: <a href="Random-number-environment-variables.html#Random-number-environment-variables" accesskey="n" rel="next">Random number environment variables</a>, Previous: <a href="Sampling-from-a-random-number-generator.html#Sampling-from-a-random-number-generator" accesskey="p" rel="previous">Sampling from a random number generator</a>, Up: <a href="Random-Number-Generation.html#Random-Number-Generation" accesskey="u" rel="up">Random Number Generation</a> &nbsp; [<a href="Function-Index.html#Function-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Auxiliary-random-number-generator-functions-1"></a>
<h3 class="section">18.5 Auxiliary random number generator functions</h3>
<p>The following functions provide information about an existing
generator.  You should use them in preference to hard-coding the generator
parameters into your own code.
</p>
<dl>
<dt><a name="index-gsl_005frng_005fname"></a>Function: <em>const char *</em> <strong>gsl_rng_name</strong> <em>(const gsl_rng * <var>r</var>)</em></dt>
<dd><p>This function returns a pointer to the name of the generator.
For example,
</p>
<div class="example">
<pre class="example">printf (&quot;r is a '%s' generator\n&quot;, 
        gsl_rng_name (r));
</pre></div>

<p>would print something like <code>r is a 'taus' generator</code>.
</p></dd></dl>

<dl>
<dt><a name="index-gsl_005frng_005fmax"></a>Function: <em>unsigned long int</em> <strong>gsl_rng_max</strong> <em>(const gsl_rng * <var>r</var>)</em></dt>
<dd><p><code>gsl_rng_max</code> returns the largest value that <code>gsl_rng_get</code>
can return.
</p></dd></dl>

<dl>
<dt><a name="index-gsl_005frng_005fmin"></a>Function: <em>unsigned long int</em> <strong>gsl_rng_min</strong> <em>(const gsl_rng * <var>r</var>)</em></dt>
<dd><p><code>gsl_rng_min</code> returns the smallest value that <code>gsl_rng_get</code>
can return.  Usually this value is zero.  There are some generators with
algorithms that cannot return zero, and for these generators the minimum
value is 1.
</p></dd></dl>

<dl>
<dt><a name="index-gsl_005frng_005fstate"></a>Function: <em>void *</em> <strong>gsl_rng_state</strong> <em>(const gsl_rng * <var>r</var>)</em></dt>
<dt><a name="index-gsl_005frng_005fsize"></a>Function: <em>size_t</em> <strong>gsl_rng_size</strong> <em>(const gsl_rng * <var>r</var>)</em></dt>
<dd><p>These functions return a pointer to the state of generator <var>r</var> and
its size.  You can use this information to access the state directly.  For
example, the following code will write the state of a generator to a
stream,
</p>
<div class="example">
<pre class="example">void * state = gsl_rng_state (r);
size_t n = gsl_rng_size (r);
fwrite (state, n, 1, stream);
</pre></div>
</dd></dl>

<dl>
<dt><a name="index-gsl_005frng_005ftypes_005fsetup"></a>Function: <em>const gsl_rng_type **</em> <strong>gsl_rng_types_setup</strong> <em>(void)</em></dt>
<dd><p>This function returns a pointer to an array of all the available
generator types, terminated by a null pointer. The function should be
called once at the start of the program, if needed.  The following code
fragment shows how to iterate over the array of generator types to print
the names of the available algorithms,
</p>
<div class="example">
<pre class="example">const gsl_rng_type **t, **t0;

t0 = gsl_rng_types_setup ();

printf (&quot;Available generators:\n&quot;);

for (t = t0; *t != 0; t++)
  {
    printf (&quot;%s\n&quot;, (*t)-&gt;name);
  }
</pre></div>
</dd></dl>

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Next: <a href="Random-number-environment-variables.html#Random-number-environment-variables" accesskey="n" rel="next">Random number environment variables</a>, Previous: <a href="Sampling-from-a-random-number-generator.html#Sampling-from-a-random-number-generator" accesskey="p" rel="previous">Sampling from a random number generator</a>, Up: <a href="Random-Number-Generation.html#Random-Number-Generation" accesskey="u" rel="up">Random Number Generation</a> &nbsp; [<a href="Function-Index.html#Function-Index" title="Index" rel="index">Index</a>]</p>
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