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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><title>R: Computes the Short Time Fourier Transform of a Vector</title> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link rel="stylesheet" type="text/css" href="R.css" /> </head><body> <table width="100%" summary="page for stft {e1071}"><tr><td>stft {e1071}</td><td style="text-align: right;">R Documentation</td></tr></table> <h2>Computes the Short Time Fourier Transform of a Vector</h2> <h3>Description</h3> <p>This function computes the Short Time Fourier Transform of a given vector <code>X</code>. </p> <p>First, time-slices of length <code>win</code> are extracted from the vector. The shift of one time-slice to the next one is given by <code>inc</code>. The values of these time-slices are smoothed by mulitplying them with a window function specified in <code>wtype</code>. For the thus obtained windows, the Fast Fourier Transform is computed.</p> <h3>Usage</h3> <pre>stft(X, win=min(80,floor(length(X)/10)), inc=min(24, floor(length(X)/30)), coef=64, wtype="hanning.window")</pre> <h3>Arguments</h3> <table summary="R argblock"> <tr valign="top"><td><code>X</code></td> <td> <p>The vector from which the stft is computed.</p> </td></tr> <tr valign="top"><td><code>win</code></td> <td> <p>Length of the window. For long vectors the default window size is 80, for short vectors the window size is chosen so that 10 windows fit in the vector.</p> </td></tr> <tr valign="top"><td><code>inc</code></td> <td> <p>Increment by which the window is shifted. For long vectors the default increment is 24, for short vectors the increment is chosen so that 30 increments fit in the vector.</p> </td></tr> <tr valign="top"><td><code>coef</code></td> <td> <p>Number of Fourier coefficients</p> </td></tr> <tr valign="top"><td><code>wtype</code></td> <td> <p>Type of window used</p> </td></tr> </table> <h3>Value</h3> <p>Object of type stft. Contains the values of the stft and information about the parameters. </p> <table summary="R valueblock"> <tr valign="top"><td><code>values</code></td> <td> <p>A matrix containing the results of the stft. Each row of the matrix contains the <code>coef</code> Fourier coefficients of one window.</p> </td></tr> <tr valign="top"><td><code>windowsize</code></td> <td> <p>The value of the parameter <code>win</code></p> </td></tr> <tr valign="top"><td><code>increment</code></td> <td> <p>The value of the parameter <code>inc</code></p> </td></tr> <tr valign="top"><td><code>windowtype</code></td> <td> <p>The value of the parameter <code>wtype</code></p> </td></tr> </table> <h3>Author(s)</h3> <p>Andreas Weingessel</p> <h3>See Also</h3> <p>plot.stft</p> <h3>Examples</h3> <pre>x<-rnorm(500) y<-stft(x) plot(y) </pre> <hr /><div style="text-align: center;">[Package <em>e1071</em> version 1.7-3 <a href="00Index.html">Index</a>]</div> </body></html>