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FFT

ANALYSE\FFT [/REMOVE [wmin wmax]]
[[s1 e1] [s2 e2] ... [s10 e10] /KILL]
[/INDEX] [/OBS] [/NOCURS]
FFT computes a Fourier transform and plots it. It acts either on a sin-
gle spectrum (from the R buffer) or on the INDEX. The default behavior
is defined with SET ACTION, but can always be ignored with /OBS or /IN-
DEX. Identically, the option /NOCURS overrides the default cursor.
Three modes are available (see subtopic for details):
- no option: the FFT is computed and plotted. The RY values are not
modified.
- /KILL allows to linearly interpolate pieces of the Fourier trans-
form, either interactively or by supplying values.
- /REMOVE indicates that the Fourier transform is to be computed from
a spectrum linearly interpolated in some intervals (specified or
taken from the last fitted profiles).
If the action is applied on the R buffer, the result (including /KILL,
if any) of the FFT is available in the variables R%FFT%X and R%FFT%Y.
There is no option to customize the FFT plot limits. A custom plot can
be done as follows:
LAS> FFT ! Fill the R%FFT%X and R%FFT%Y arrays
LAS> G\LIMITS /VARIABLES R%FFT%X R%FFT%Y ! Auto X and Y limits
LAS> G\LIMITS 0.0 1.0 = = ! Override X limits with custom values
LAS> CLEAR
LAS> G\BOX
LAS> G\HISTO R%FFT%X R%FFT%Y
LAS> G\LABEL "Inverse Frequency (MHz\\u-1\d)" /X

**Subsections**

Gildas manager
2019-02-20