# stft: Computes the Short Time Fourier Transform of a Vector In e1071: Misc Functions of the Department of Statistics, Probability Theory Group (Formerly: E1071), TU Wien

## Description

This function computes the Short Time Fourier Transform of a given vector `X`.

First, time-slices of length `win` are extracted from the vector. The shift of one time-slice to the next one is given by `inc`. The values of these time-slices are smoothed by mulitplying them with a window function specified in `wtype`. For the thus obtained windows, the Fast Fourier Transform is computed.

## Usage

 ```1 2``` ```stft(X, win=min(80,floor(length(X)/10)), inc=min(24, floor(length(X)/30)), coef=64, wtype="hanning.window") ```

## Arguments

 `X` The vector from which the stft is computed. `win` 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. `inc` 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. `coef` Number of Fourier coefficients `wtype` Type of window used

## Value

Object of type stft. Contains the values of the stft and information about the parameters.

 `values` A matrix containing the results of the stft. Each row of the matrix contains the `coef` Fourier coefficients of one window. `windowsize` The value of the parameter `win` `increment` The value of the parameter `inc` `windowtype` The value of the parameter `wtype`

## Author(s)

Andreas Weingessel

 ```1 2 3``` ```x<-rnorm(500) y<-stft(x) plot(y) ```