FFTCMPLX

Scicos Block
fr - eng

Fast Fourier Transform block

$\epsfig{file=FFTCMPLX_f.eps,height=90pt}$

Fast Fourier Transform block

Description

That block computes a direct or backward Fast Fourier Transform. Regular inputs/outputs are the real and imaginary part of a complex number. They are vectorial.

The parameter Mode details which algorithms are used to compute the FFT.

If Mode=0 the interfacing function will automatically choose between the fft842 and dfftmx algorithms. The first are more powerful for computational time but only work for size of vectors with 2 power and for size less than 2^15. The second algorithm (dfftmx) can work for any size of vector but is more slow. If the size of the input vector is a 2 power and less than 2^15 fft842 will be used else this is dfftmx.

Mode=1 is to always use dfftmx.

If the 'Modnum' toolbox have been build with the FFTW library the block will automatically use that library in any case.

Dialog box

$\begin{figure}\begin{center} \epsfig{file=FFTCMPLX_f_gui.eps,width=300pt} \end{center}\end{figure}$

Size of inputs
The size of the input vectors.
Type 'vec' of size 1.
Inherit (no:0, yes:1)
Herits events by its regular input ports (disable the event input port).
Type 'vec' of size 1.
Type of fft (-1:direct/1:indirect)
Use -1 for direct fft and 1 for indirect fft.
Type 'vec' of size 1.
Mode (0:Auto/1:Dfftmx)
Use 0 to automatically switch betwenn fft842/dfftmx algorithms or force dfftmx with 1.
Type 'vec' of size 1.

Default properties

always active: no
direct-feedthrough: yes
zero-crossing: no
mode: no
regular inputs:
- port 1 : size [256,1] / type 1
- port 2 : size [256,1] / type 1
regular outputs:
- port 1 : size [256,1] / type 1
- port 2 : size [256,1] / type 1
number/sizes of activation inputs: 0
number/sizes of activation outputs: 0
continuous-time state: no
discrete-time state: no
object discrete-time state: no
name of computational function: fftcmplx