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 1.5-2

Index]