Declaration: SpdcOfSpectrum(SpdcIx, ix, iy, it: integer; var errnum: integer): double;
Calculates the descriptor SpdcIx of the spectrum of the pixel specified by ix, iy and it (x and y positions and time slot, respectively). The parameter SpdcIx is the index pointing to the list of spectral descriptors. The function returns the calculated value if errnum is zero. A non-zero value of errnum indicates one of the following errors:
-1 .... the spectral descriptor is undefined (index points to a non-existing spectral descriptor)
-2 .... the specified pixel does not exists (ix, iy, and/or it are out of range)
Hint: Please note that this function is rather inefficient and should be used only if the descriptors of a small number of pixels are to be calculated. In order to calculate the spectral descriptor of an entire image the function CalcSpdcMatrix should be used.

Last Update: 2020-Jšn-04