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<title>Memory Allocation - FFTW 3.2.2</title>
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<h4 class="subsection">4.1.3 Memory Allocation</h4>
<pre class="example"> void *fftw_malloc(size_t n);
void fftw_free(void *p);
</pre>
<p><a name="index-fftw_005fmalloc-142"></a><a name="index-fftw_005ffree-143"></a>
These are functions that behave identically to <code>malloc</code> and
<code>free</code>, except that they guarantee that the returned pointer obeys
any special alignment restrictions imposed by any algorithm in FFTW
(e.g. for SIMD acceleration). See <a href="Data-Alignment.html#Data-Alignment">Data Alignment</a>.
<a name="index-alignment-144"></a>
Data allocated by <code>fftw_malloc</code> <em>must</em> be deallocated by
<code>fftw_free</code> and not by the ordinary <code>free</code>.
<p>These routines simply call through to your operating system's
<code>malloc</code> or, if necessary, its aligned equivalent
(e.g. <code>memalign</code>), so you normally need not worry about any
significant time or space overhead. You are <em>not required</em> to use
them to allocate your data, but we strongly recommend it.
<p>Note: in C++, just as with ordinary <code>malloc</code>, you must typecast
the output of <code>fftw_malloc</code> to whatever pointer type you are
allocating.
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