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SMOOTH copies R into T, then degrades the frequency/velocity resolution
of R according to the selected method. If the R buffer also provides As-
sociated Arrays, the smoothing method is also applied to them, except
for the method NOISE where this is not relevant. It is not yet possible
to provide a custom smoothing method for the Associated Arrays.
The arguments are used to specify the method:
- HANNING (no argument, default)
The new spectrum has twice less channels and twice less resolution.
Each output channel RY[J] is evaluated from the inputs channels as
TY[I-1]/2 + TY[I] + TY[I+1]/2.
- HANNING Width Spacing [Shift]
The Hann window width is ruled by the "Width" variable, and the out-
put channel spacing by the "Spacing" variable. By default, the left
boundaries of the first input and output channels are aligned, but
user can shift the output grid by any fraction of channel using a
custom shift ("Shift" variable). All values are expected in lower
axis unit. Invoking SMOOTH HANNING 4*res 2*res 0.5*res (where "res"
is the lower axis resolution) is equivalent to the default SMOOTH
HANNING (no argument, as described above), except it uses the gener-
ic (less efficient) engine.
- GAUSS Width
Convolves (by multiplication in the Fourier plane) by a gaussian of
specified width in current X units. Because this method does not
support bad values in the Fourier plane, bad channels are interpo-
lated before use.
- BOX Nchan
Averages Nchan adjacent channels to produce a spectrum with Nchan
less resolution and channels.
- NOISE Flux Nc
For each channel, sums at most Nc neighbouring channels until a to-
tal flux Flux is reached in the sum. Then attributes the average
value (sum divided by number of channels added) to the channel. This
smoothing is non-uniform, strictly positive, and has an obvious ten-
dency to produce wings...