outputFile contains a column f for the frequency, along with one or more columns for each independent variable. By default, outputFile has one column named FFTindepName containing the magnitude of the FFT for each independent variable. If -fullOutput is specified, outputFile contains additional columns for, respectively, the phase (or argument), real part, and imaginary part of the FFT: ArgindepName, RealindepName, and ImagindepName. If power-spectral-density output is requested, then a column PSDindepName is also created.
outputFile also contains two parameters, fftFrequencies and fftFrequencySpacing, giving the number of frequencies and the frequency spacing, respectively.
pipe[=input][,output]-- The standard SDDS Toolkit pipe option.
-padWithZeros-- Specifies that the independent data should be padded with zeros to make the number of points equal to the nearest power of two. In some cases, this will result in significantly greater speed.
-truncate-- Specifies that the data should be truncated so that the number of points is the largest product of primes from 2 to 19 not greater than the original number of points. In some cases, this will result in significantly greater speed.
normalize-- Specifies that FFT's will be normalized to give a maximum magnitude of 1.
suppressAverage-- Specifies that the average value of the data will be subtracted from every point prior to taking the FFT. This may improve accuracy and visibility of small components.
complexInput-- Specifies that the names of the input columns are of the form Real<rootname> and Imag<rootname>, giving the real and imaginary part of a function to be analyzed. In this case, the <depen-quantity> entries in the -columns option give the rootname, not the full quantity name. It has options folded and unfolded, unfolded means the input frequency space input is unfolded and it must have negative frequency. default is "folded", If no option is given, and if the input file has "SpectrumFolded" parameter, then it will be defined by this parameter.
fullOutput-- Specifies that in addition to the magnitude, the phase, real part, and imaginary part of each FFT will be included in the output. It also has folded and unfolded options, while the unfold option outputs the unfolded frequency-space (full FFT spectrum), but the folded option outputs the folded spectrum (half FFT).
inverse-- produce inverse fourier transform. when it is given, the output is always unfolded spectrum and it only works with complexInput that has imaginary data.
psdOutput-- Specifies that in in addition to ordinary FFT data, the power-spectral-densities will also be included in the output. The units of the PSD are of the form , where x (t) represents the units of the independent (dependent) variable. These units are conventional with PSDs, which are normalized to the frequency spacing so that integrating the PSD gives the signal power.
|Real Number||Real Number||Imaginary Number||output option|
|Real Number||Imaginary Number||Condition||Input option||Real Number||Imaginary Number||output option|
|Real Number||Imaginary Number||Condition||Input option||Real Number||Imaginary Number|