This routine performs the forward or
inverse FFT of a 2D map. The FFT of the data are stored in a 3-dimensional array with dimensions
xfrequency, yfrequency, component (where component is a dimension of length 2 holding the real and
imaginary parts, or ampliude and phase if in polar form). The inverse flag is used to transform back to
the spatial domain from the frequency domain. If the data are already in the requested domain, the
ouput file is simply a copy of the input file.
AZAVPSPEC = _LOGICAL (Read)
If
true, calculate the azimuthally-averaged angular power power spectrum. POLAR and
POWER are set implicitly. [FALSE]
IN = NDF (Read)
Input files to be transformed.
INVERSE = _LOGICAL (Read)
Perform inverse transform. [FALSE]
MSG_FILTER =
_CHAR (Read)
Control the verbosity of the application. Values can be NONE (no messages),
QUIET (minimal messages), NORMAL, VERBOSE, DEBUG or ALL. [NORMAL]
OUT
= NDF (Write)
Output transformed files.
POLAR = _LOGICAL (Update)
Use polar
representation (amplitude, argument) of FFT. [FALSE]
POWER = _LOGICAL (Update)
Use
polar representation of FFT with squared amplitudes divided by the frequency bin spacing
(gives a power spectral density, PSD). [FALSE]
ZEROBAD = _LOGICAL (Read)
Zero
any bad values in the data before taking FFT. [TRUE]
Transforming data loses
the VARIANCE and QUALITY components.