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cannam@127: <title>FFTW 3.3.5: Memory Allocation</title>
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cannam@127: <a name="Memory-Allocation"></a>
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cannam@127: Previous: <a href="Precision.html#Precision" accesskey="p" rel="prev">Precision</a>, Up: <a href="Data-Types-and-Files.html#Data-Types-and-Files" accesskey="u" rel="up">Data Types and Files</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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cannam@127: <hr>
cannam@127: <a name="Memory-Allocation-1"></a>
cannam@127: <h4 class="subsection">4.1.3 Memory Allocation</h4>
cannam@127:
cannam@127: <div class="example">
cannam@127: <pre class="example">void *fftw_malloc(size_t n);
cannam@127: void fftw_free(void *p);
cannam@127: </pre></div>
cannam@127: <a name="index-fftw_005fmalloc-3"></a>
cannam@127: <a name="index-fftw_005ffree-2"></a>
cannam@127:
cannam@127: <p>These are functions that behave identically to <code>malloc</code> and
cannam@127: <code>free</code>, except that they guarantee that the returned pointer obeys
cannam@127: any special alignment restrictions imposed by any algorithm in FFTW
cannam@127: (e.g. for SIMD acceleration). See <a href="SIMD-alignment-and-fftw_005fmalloc.html#SIMD-alignment-and-fftw_005fmalloc">SIMD alignment and fftw_malloc</a>.
cannam@127: <a name="index-alignment"></a>
cannam@127: </p>
cannam@127:
cannam@127: <p>Data allocated by <code>fftw_malloc</code> <em>must</em> be deallocated by
cannam@127: <code>fftw_free</code> and not by the ordinary <code>free</code>.
cannam@127: </p>
cannam@127: <p>These routines simply call through to your operating system’s
cannam@127: <code>malloc</code> or, if necessary, its aligned equivalent
cannam@127: (e.g. <code>memalign</code>), so you normally need not worry about any
cannam@127: significant time or space overhead. You are <em>not required</em> to use
cannam@127: them to allocate your data, but we strongly recommend it.
cannam@127: </p>
cannam@127: <p>Note: in C++, just as with ordinary <code>malloc</code>, you must typecast
cannam@127: the output of <code>fftw_malloc</code> to whatever pointer type you are
cannam@127: allocating.
cannam@127: <a name="index-C_002b_002b-4"></a>
cannam@127: </p>
cannam@127:
cannam@127: <p>We also provide the following two convenience functions to allocate
cannam@127: real and complex arrays with <code>n</code> elements, which are equivalent
cannam@127: to <code>(double *) fftw_malloc(sizeof(double) * n)</code> and
cannam@127: <code>(fftw_complex *) fftw_malloc(sizeof(fftw_complex) * n)</code>,
cannam@127: respectively:
cannam@127: </p>
cannam@127: <div class="example">
cannam@127: <pre class="example">double *fftw_alloc_real(size_t n);
cannam@127: fftw_complex *fftw_alloc_complex(size_t n);
cannam@127: </pre></div>
cannam@127: <a name="index-fftw_005falloc_005freal-1"></a>
cannam@127: <a name="index-fftw_005falloc_005fcomplex-2"></a>
cannam@127:
cannam@127: <p>The equivalent functions in other precisions allocate arrays of <code>n</code>
cannam@127: elements in that precision. e.g. <code>fftwf_alloc_real(n)</code> is
cannam@127: equivalent to <code>(float *) fftwf_malloc(sizeof(float) * n)</code>.
cannam@127: <a name="index-precision-4"></a>
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