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			94 lines
		
	
	
		
			4.3 KiB
		
	
	
	
		
			HTML
		
	
	
	
	
	
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<!-- This manual is for FFTW
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(version 3.3.10, 10 December 2020).
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Copyright (C) 2003 Matteo Frigo.
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Copyright (C) 2003 Massachusetts Institute of Technology.
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<title>FFTW Constants in Fortran (FFTW 3.3.10)</title>
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<span id="FFTW-Constants-in-Fortran"></span><div class="header">
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Next: <a href="FFTW-Execution-in-Fortran.html" accesskey="n" rel="next">FFTW Execution in Fortran</a>, Previous: <a href="Fortran_002dinterface-routines.html" accesskey="p" rel="prev">Fortran-interface routines</a>, Up: <a href="Calling-FFTW-from-Legacy-Fortran.html" accesskey="u" rel="up">Calling FFTW from Legacy Fortran</a>   [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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<span id="FFTW-Constants-in-Fortran-1"></span><h3 class="section">8.2 FFTW Constants in Fortran</h3>
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<p>When creating plans in FFTW, a number of constants are used to specify
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options, such as <code>FFTW_MEASURE</code> or <code>FFTW_ESTIMATE</code>.  The
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same constants must be used with the wrapper routines, but of course the
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C header files where the constants are defined can’t be incorporated
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directly into Fortran code.
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</p>
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<p>Instead, we have placed Fortran equivalents of the FFTW constant
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definitions in the file <code>fftw3.f</code>, which can be found in the same
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directory as <code>fftw3.h</code>.  If your Fortran compiler supports a
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preprocessor of some sort, you should be able to <code>include</code> or
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<code>#include</code> this file; otherwise, you can paste it directly into
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your code.
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</p>
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<span id="index-flags-9"></span>
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<p>In C, you combine different flags (like <code>FFTW_PRESERVE_INPUT</code> and
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<code>FFTW_MEASURE</code>) using the ‘<samp><code>|</code></samp>’ operator; in Fortran
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you should just use ‘<samp><code>+</code></samp>’.  (Take care not to add in the
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same flag more than once, though.  Alternatively, you can use the
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<code>ior</code> intrinsic function standardized in Fortran 95.)
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</p>
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