next up previous contents index
Next: FFT /KILL Up: ANALYSE Language Internal Help Previous: DRAW WINDOW   Contents   Index


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 2018-02-24