R: Computes the Short Time Fourier Transform of a Vector

stft {e1071} | R Documentation

## Computes the Short Time Fourier Transform of a Vector

### 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

    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

### See Also

plot.stft

### Examples

    x<-rnorm(500)
    y<-stft(x)
    plot(y)

[Package e1071 version 1.7-4 Index]