FFTn (FPScript)
Computes the complex Fourier transform of the argument.
Syntax
FFTn(Signal [ , Fold = TRUE ])
The syntax of the FFTn function consists of the following parts:
Part |
Description |
|---|---|
Signal |
The data set to be transformed. Permitted data structures are data series, data matrix, signal und signal series. All numeric data types are permitted. For the X component additional restrictions do apply.The values must have a constant non-zero spacing. If the argument is a list, then the function is executed for each element of the list and the result is also a list. |
Fold |
This property is only taken into account if the Signal is real, i.e. if the calculated spectrum is symmetrical. The value TRUE specifies that the positive and negative spectral components are to be superimposed. In this case, all coefficients except the first one will be multiplied with a factor of 2. Permitted data structures are scalar value. Supported data types are Boolean value. If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated. If this argument is omitted, it will be set to the default value TRUE. |
Remarks
If Signal is real, then the calculated spectrum is symmetrical and only positive frequencies will be output. In this case, the spectrum only has half of the time signal's values.
For a complex spectrum, the "negative" frequencies are also calculated. These are, however, not saved before the positive frequencies, but rather after them. This is also mathematically correct, since the Fourier transform of a sampled signal is periodic and the negative frequencies re-appear after the positive frequencies.
If Signal is a signal or signal series with time values in the X component, then these are transformed into the respective frequencies.
Available in
FlexPro Basic, Professional, Developer Suite
Examples
FFTn(Signal(Sin(2. * PI * 25 * (1000, 0, 0.001)), (1000, 0, 0.001))) |
Calculates the complex Fourier transform of a sinusoidal signal with the frequency 25 Hz. |