scilab/modules/signal_processing/help/en_US/mfft.xml

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <refentry xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:svg="http://www.w3.org/2000/svg" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:db="http://docbook.org/ns/docbook" version="5.0-subset Scilab" xml:lang="en" xml:id="mfft">
   3     <refnamediv>
   4         <refname>mfft</refname>
   5         <refpurpose> multi-dimensional fft</refpurpose>
   6     </refnamediv>
   7     <refsynopsisdiv>
   8         <title>Calling Sequence</title>
   9         <synopsis>[xk]=mfft(x,flag,dim)</synopsis>
  10     </refsynopsisdiv>
  11     <refsection>
  12         <title>Arguments</title>
  13         <variablelist>
  14             <varlistentry>
  15                 <term>x</term>
  16                 <listitem>
  17                     <para>
  18                         <literal>x(i,j,k,...)</literal> input signal in the form of a row vector whose values are arranged so that the i index runs the quickest, followed by the j index, etc.
  19                     </para>
  20                 </listitem>
  21             </varlistentry>
  22             <varlistentry>
  23                 <term>flag</term>
  24                 <listitem>
  25                     <para>(-1) FFT or (1) inverse FFT</para>
  26                 </listitem>
  27             </varlistentry>
  28             <varlistentry>
  29                 <term>dim</term>
  30                 <listitem>
  31                     <para>
  32                         dimension vector which gives the number of values of <literal>x</literal> for each of its indices
  33                     </para>
  34                 </listitem>
  35             </varlistentry>
  36             <varlistentry>
  37                 <term>xk</term>
  38                 <listitem>
  39                     <para>
  40                         output of multidimensional fft in same format as for <literal>x</literal>
  41                     </para>
  42                 </listitem>
  43             </varlistentry>
  44         </variablelist>
  45     </refsection>
  46     <refsection>
  47         <title>Description</title>
  48         <para>
  49             FFT for a multi-dimensional signal
  50         </para>
  51         <para>
  52             For example for a three dimensional vector which has three points
  53             along its first dimension, two points along its second
  54             dimension and three points along its third dimension the row
  55             vector is arranged as follows
  56         </para>
  57         <programlisting role="no-scilab-exec"><![CDATA[
  58 x=[x(1,1,1),x(2,1,1),x(3,1,1),
  59    x(1,2,1),x(2,2,1),x(3,2,1),
  60    x(1,1,2),x(2,1,2),x(3,1,2),
  61    x(1,2,2),x(2,2,2),x(3,2,2),
  62    x(1,1,3),x(2,1,3),x(3,1,3),
  63    x(1,2,3),x(2,2,3),x(3,2,3)]
  64  ]]></programlisting>
  65         <para>
  66             and the <literal>dim</literal> vector is: <literal>dim=[3,2,3]</literal>
  67         </para>
  68     </refsection>
  69     <refsection>
  70         <title>Examples</title>
  71         <programlisting role="example"><![CDATA[
  72 y1=matrix(1:6,2,3)
  73 y2=matrix(7:12,2,3)
  74 y=matrix([y1,y2],1,12)
  75 yf=mfft(y,-1,[2 3 2])
  76  ]]></programlisting>
  77     </refsection>
  78
  79 </refentry>