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<title>GNU Scientific Library – Reference Manual: Initializing the Solver</title>
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<a name="Initializing-the-Solver"></a>
<div class="header">
<p>
Next: <a href="Providing-the-function-to-solve.html#Providing-the-function-to-solve" accesskey="n" rel="next">Providing the function to solve</a>, Previous: <a href="Root-Finding-Caveats.html#Root-Finding-Caveats" accesskey="p" rel="previous">Root Finding Caveats</a>, Up: <a href="One-dimensional-Root_002dFinding.html#One-dimensional-Root_002dFinding" accesskey="u" rel="up">One dimensional Root-Finding</a> [<a href="Function-Index.html#Function-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Initializing-the-Solver-1"></a>
<h3 class="section">34.3 Initializing the Solver</h3>
<dl>
<dt><a name="index-gsl_005froot_005ffsolver_005falloc"></a>Function: <em>gsl_root_fsolver *</em> <strong>gsl_root_fsolver_alloc</strong> <em>(const gsl_root_fsolver_type * <var>T</var>)</em></dt>
<dd><a name="index-gsl_005froot_005ffsolver"></a>
<a name="index-gsl_005froot_005ffsolver_005ftype"></a>
<p>This function returns a pointer to a newly allocated instance of a
solver of type <var>T</var>. For example, the following code creates an
instance of a bisection solver,
</p>
<div class="example">
<pre class="example">const gsl_root_fsolver_type * T
= gsl_root_fsolver_bisection;
gsl_root_fsolver * s
= gsl_root_fsolver_alloc (T);
</pre></div>
<p>If there is insufficient memory to create the solver then the function
returns a null pointer and the error handler is invoked with an error
code of <code>GSL_ENOMEM</code>.
</p></dd></dl>
<dl>
<dt><a name="index-gsl_005froot_005ffdfsolver_005falloc"></a>Function: <em>gsl_root_fdfsolver *</em> <strong>gsl_root_fdfsolver_alloc</strong> <em>(const gsl_root_fdfsolver_type * <var>T</var>)</em></dt>
<dd><a name="index-gsl_005froot_005ffdfsolver"></a>
<a name="index-gsl_005froot_005ffdfsolver_005ftype"></a>
<p>This function returns a pointer to a newly allocated instance of a
derivative-based solver of type <var>T</var>. For example, the following
code creates an instance of a Newton-Raphson solver,
</p>
<div class="example">
<pre class="example">const gsl_root_fdfsolver_type * T
= gsl_root_fdfsolver_newton;
gsl_root_fdfsolver * s
= gsl_root_fdfsolver_alloc (T);
</pre></div>
<p>If there is insufficient memory to create the solver then the function
returns a null pointer and the error handler is invoked with an error
code of <code>GSL_ENOMEM</code>.
</p></dd></dl>
<dl>
<dt><a name="index-gsl_005froot_005ffsolver_005fset"></a>Function: <em>int</em> <strong>gsl_root_fsolver_set</strong> <em>(gsl_root_fsolver * <var>s</var>, gsl_function * <var>f</var>, double <var>x_lower</var>, double <var>x_upper</var>)</em></dt>
<dd><p>This function initializes, or reinitializes, an existing solver <var>s</var>
to use the function <var>f</var> and the initial search interval
[<var>x_lower</var>, <var>x_upper</var>].
</p></dd></dl>
<dl>
<dt><a name="index-gsl_005froot_005ffdfsolver_005fset"></a>Function: <em>int</em> <strong>gsl_root_fdfsolver_set</strong> <em>(gsl_root_fdfsolver * <var>s</var>, gsl_function_fdf * <var>fdf</var>, double <var>root</var>)</em></dt>
<dd><p>This function initializes, or reinitializes, an existing solver <var>s</var>
to use the function and derivative <var>fdf</var> and the initial guess
<var>root</var>.
</p></dd></dl>
<dl>
<dt><a name="index-gsl_005froot_005ffsolver_005ffree"></a>Function: <em>void</em> <strong>gsl_root_fsolver_free</strong> <em>(gsl_root_fsolver * <var>s</var>)</em></dt>
<dt><a name="index-gsl_005froot_005ffdfsolver_005ffree"></a>Function: <em>void</em> <strong>gsl_root_fdfsolver_free</strong> <em>(gsl_root_fdfsolver * <var>s</var>)</em></dt>
<dd><p>These functions free all the memory associated with the solver <var>s</var>.
</p></dd></dl>
<dl>
<dt><a name="index-gsl_005froot_005ffsolver_005fname"></a>Function: <em>const char *</em> <strong>gsl_root_fsolver_name</strong> <em>(const gsl_root_fsolver * <var>s</var>)</em></dt>
<dt><a name="index-gsl_005froot_005ffdfsolver_005fname"></a>Function: <em>const char *</em> <strong>gsl_root_fdfsolver_name</strong> <em>(const gsl_root_fdfsolver * <var>s</var>)</em></dt>
<dd><p>These functions return a pointer to the name of the solver. For example,
</p>
<div class="example">
<pre class="example">printf ("s is a '%s' solver\n",
gsl_root_fsolver_name (s));
</pre></div>
<p>would print something like <code>s is a 'bisection' solver</code>.
</p></dd></dl>
<hr>
<div class="header">
<p>
Next: <a href="Providing-the-function-to-solve.html#Providing-the-function-to-solve" accesskey="n" rel="next">Providing the function to solve</a>, Previous: <a href="Root-Finding-Caveats.html#Root-Finding-Caveats" accesskey="p" rel="previous">Root Finding Caveats</a>, Up: <a href="One-dimensional-Root_002dFinding.html#One-dimensional-Root_002dFinding" accesskey="u" rel="up">One dimensional Root-Finding</a> [<a href="Function-Index.html#Function-Index" title="Index" rel="index">Index</a>]</p>
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