annotate src/fftw-3.3.8/doc/html/Wisdom-of-Fortran_003f.html @ 82:d0c2a83c1364

Add FFTW 3.3.8 source, and a Linux build
author Chris Cannam
date Tue, 19 Nov 2019 14:52:55 +0000
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Chris@82 25 <title>FFTW 3.3.8: Wisdom of Fortran?</title>
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Chris@82 71 <a name="Wisdom-of-Fortran_003f"></a>
Chris@82 72 <div class="header">
Chris@82 73 <p>
Chris@82 74 Previous: <a href="Fortran-Examples.html#Fortran-Examples" accesskey="p" rel="prev">Fortran Examples</a>, Up: <a href="Calling-FFTW-from-Legacy-Fortran.html#Calling-FFTW-from-Legacy-Fortran" accesskey="u" rel="up">Calling FFTW from Legacy Fortran</a> &nbsp; [<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>
Chris@82 75 </div>
Chris@82 76 <hr>
Chris@82 77 <a name="Wisdom-of-Fortran_003f-1"></a>
Chris@82 78 <h3 class="section">8.5 Wisdom of Fortran?</h3>
Chris@82 79
Chris@82 80 <p>In this section, we discuss how one can import/export FFTW wisdom
Chris@82 81 (saved plans) to/from a Fortran program; we assume that the reader is
Chris@82 82 already familiar with wisdom, as described in <a href="Words-of-Wisdom_002dSaving-Plans.html#Words-of-Wisdom_002dSaving-Plans">Words of Wisdom-Saving Plans</a>.
Chris@82 83 </p>
Chris@82 84 <a name="index-portability-8"></a>
Chris@82 85 <p>The basic problem is that is difficult to (portably) pass files and
Chris@82 86 strings between Fortran and C, so we cannot provide a direct Fortran
Chris@82 87 equivalent to the <code>fftw_export_wisdom_to_file</code>, etcetera,
Chris@82 88 functions. Fortran interfaces <em>are</em> provided for the functions
Chris@82 89 that do not take file/string arguments, however:
Chris@82 90 <code>dfftw_import_system_wisdom</code>, <code>dfftw_import_wisdom</code>,
Chris@82 91 <code>dfftw_export_wisdom</code>, and <code>dfftw_forget_wisdom</code>.
Chris@82 92 <a name="index-dfftw_005fimport_005fsystem_005fwisdom"></a>
Chris@82 93 <a name="index-dfftw_005fimport_005fwisdom"></a>
Chris@82 94 <a name="index-dfftw_005fexport_005fwisdom"></a>
Chris@82 95 <a name="index-dfftw_005fforget_005fwisdom"></a>
Chris@82 96 </p>
Chris@82 97
Chris@82 98 <p>So, for example, to import the system-wide wisdom, you would do:
Chris@82 99 </p>
Chris@82 100 <div class="example">
Chris@82 101 <pre class="example"> integer isuccess
Chris@82 102 call dfftw_import_system_wisdom(isuccess)
Chris@82 103 </pre></div>
Chris@82 104
Chris@82 105 <p>As usual, the C return value is turned into a first parameter;
Chris@82 106 <code>isuccess</code> is non-zero on success and zero on failure (e.g. if
Chris@82 107 there is no system wisdom installed).
Chris@82 108 </p>
Chris@82 109 <p>If you want to import/export wisdom from/to an arbitrary file or
Chris@82 110 elsewhere, you can employ the generic <code>dfftw_import_wisdom</code> and
Chris@82 111 <code>dfftw_export_wisdom</code> functions, for which you must supply a
Chris@82 112 subroutine to read/write one character at a time. The FFTW package
Chris@82 113 contains an example file <code>doc/f77_wisdom.f</code> demonstrating how to
Chris@82 114 implement <code>import_wisdom_from_file</code> and
Chris@82 115 <code>export_wisdom_to_file</code> subroutines in this way. (These routines
Chris@82 116 cannot be compiled into the FFTW library itself, lest all FFTW-using
Chris@82 117 programs be required to link with the Fortran I/O library.)
Chris@82 118 </p>
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