IRFFTn (FPScript)
Computes the real inverse Fourier transform of the argument.
Syntax
IRFFTn(Spectrum [ , Unfold = TRUE ])
The syntax of the IRFFTn function consists of the following parts:
Part |
Description |
|---|---|
Spectrum |
The complex Fourier series, which is to be transformed inversely in a real result. Permitted data structures are data series, data matrix, signal und signal series. All complex 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. |
Unfold |
The value TRUE specifies that the positive and negative spectral components in Spectrum are superimposed. In this case, all coefficients except the first one will be multiplied with a factor of 0.5 before the reverse discrete transform. 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
Spectrum must be the transform of a real time signal, i.e. must only contain the positive frequencies. If the spectrum that you want to transform originates from a complex time signal, then you must use the IFFTn function. You can find more information under the FFTn function. If Spectrum is a signal or signal series with frequencies in the X component, then these are transformed into the respective time values.
Available in
FlexPro Basic, Professional, Developer Suite
Examples
Dim fft = FFTn(Signal(Sin(2. * PI * 25 * (1000, 0, 0.001)), (1000, 0, 0.001)))
IRFFTn(fft)
Computes the real inverse Fourier transform of a spectrum. This is a cosine signal with the frequency of 25 Hz.