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<?xml version="1.0" encoding="UTF-8"?>
<!--
*
* This help file was generated from stft.sci using help_from_sci().
*
-->
<refentry version="5.0-subset Scilab" xml:id="stft" xml:lang="en"
xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:svg="http://www.w3.org/2000/svg"
xmlns:ns3="http://www.w3.org/1999/xhtml"
xmlns:mml="http://www.w3.org/1998/Math/MathML"
xmlns:scilab="http://www.scilab.org"
xmlns:db="http://docbook.org/ns/docbook">
<refnamediv>
<refname>stft</refname>
<refpurpose>Compute the short-time Fourier transform of the vector X</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Calling Sequence</title>
<synopsis>
Y = stft (X)
Y = stft (X, WIN_SIZE)
Y = stft (X, WIN_SIZE, INC)
Y = stft (X, WIN_SIZE, INC, NUM_COEF)
Y = stft (X, WIN_SIZE, INC, NUM_COEF, WIN_TYPE)
[Y,C] = stft (X)
[Y,C] = stft (X, WIN_SIZE)
[Y,C] = stft (X, WIN_SIZE, INC)
[Y,C] = stft (X, WIN_SIZE, INC, NUM_COEF)
[Y,C] = stft (X, WIN_SIZE, INC, NUM_COEF, WIN_TYPE)
</synopsis>
</refsynopsisdiv>
<refsection>
<title>Parameters</title>
<variablelist>
<varlistentry><term>X:</term>
<listitem><para> Real scalar or vector</para></listitem></varlistentry>
<varlistentry><term>WIN_SIZE:</term>
<listitem><para> Size of the window used</para></listitem></varlistentry>
<varlistentry><term>INC:</term>
<listitem><para> Increment</para></listitem></varlistentry>
<varlistentry><term>WIN_TYPE:</term>
<listitem><para> Type of window</para></listitem></varlistentry>
</variablelist>
</refsection>
<refsection>
<title>Description</title>
<para>
Compute the short-time Fourier transform of the vector X with NUM_COEF coefficients by applying a window of WIN_SIZE data points and an increment of INC points.
</para>
<para>
Before computing the Fourier transform, one of the following windows is applied:
</para>
<para>
"hanning" -> win_type = 1
</para>
<para>
"hamming" -> win_type = 2
</para>
<para>
"rectangle" -> win_type = 3
</para>
<para>
The window names can be passed as strings or by the WIN_TYPE number.
</para>
<para>
The following defaults are used for unspecified arguments:WIN_SIZE= 80, INC = 24, NUM_COEF = 64, and WIN_TYPE = 1.
</para>
<para>
Y = stft (X, ...)' returns the absolute values of the Fourier coefficients according to the NUM_COEF positive frequencies.
</para>
<para>
'[Y, C] = stft (x, ...)' returns the entire STFT-matrix Y and a 3-element vector C containing the window size, increment, and window type, which is needed by the 'synthesis' function.
</para>
</refsection>
</refentry>
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