Unit:  SDL_fourier  Class:  TFastFourier  Declaration:  property SpectrumSize: integer; 
The property SpectrumSize determines the length of the data array used for the Fourier transform. SpectrumSize must be a power of 2, with a minimum value of 4 and a maximum of 16 million points. Setting SpectrumSize to a value other than a power of 2 will result in an error message. Please note that the data buffers RealSpec and ImagSpec are cleared if the SpectrumSize is changed.
Hint 1: 
If the number of data to be transformed differs from a power of 2, you should fill the unused elements of the data buffer with zero values. 
Hint 2: 
In the Light Edition the size of the spectrum is restricted to 1024 data points. 
