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author Chris Cannam
date Wed, 07 Sep 2016 10:40:32 +0100
parents 26056e866c29
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Chris@19 56
Chris@19 57 <h4 class="subsection">4.5.1 Interleaved and split arrays</h4>
Chris@19 58
Chris@19 59 <p>The guru interface supports two representations of complex numbers,
Chris@19 60 which we call the interleaved and the split format.
Chris@19 61
Chris@19 62 <p>The <dfn>interleaved</dfn> format is the same one used by the basic and
Chris@19 63 advanced interfaces, and it is documented in <a href="Complex-numbers.html#Complex-numbers">Complex numbers</a>.
Chris@19 64 In the interleaved format, you provide pointers to the real part of a
Chris@19 65 complex number, and the imaginary part understood to be stored in the
Chris@19 66 next memory location.
Chris@19 67 <a name="index-interleaved-format-243"></a>
Chris@19 68
Chris@19 69 <p>The <dfn>split</dfn> format allows separate pointers to the real and
Chris@19 70 imaginary parts of a complex array.
Chris@19 71 <a name="index-split-format-244"></a>
Chris@19 72
Chris@19 73 <p>Technically, the interleaved format is redundant, because you can
Chris@19 74 always express an interleaved array in terms of a split array with
Chris@19 75 appropriate pointers and strides. On the other hand, the interleaved
Chris@19 76 format is simpler to use, and it is common in practice. Hence, FFTW
Chris@19 77 supports it as a special case.
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