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SOLVE AMPLITUDE

        CLIC\SOLVE AMPLITUDE  [/PLOT] [/BREAK kind time [kind time ...]
        [/POLYNOMIAL [degree]] [/WEIGHT] [/RESET]

    This command fits a mathematical function into the measured amplitude of
    the sources in the current index (presumably  calibrators).   This  data
    must  have  been selected and plotted in axes : SET X TIME and SET Y AM-
    PLITUDE for the baselines and bands of interest, specified by the corre-
    sponding SET commands. The calibration function is kept in memory.  Com-
    mand STORE AMPLITUDE should be used next to store this function  in  the
    header of source observations, after a change in the index to select the
    appropriate scans.

    SOLVE AMPLITUDE internally  and  temporarily  resets  SET  AMPLITUDE  to
    SCALED.

    In  antenna mode (selected by SET AMPLITUDE ANTENNA), the averaged phase
    and amplitude closures are computed, as well as  their  standard  devia-
    tions.  The  phase closures should be close to zero, while the amplitude
    closures should be close to 100%. Strong deviations  of  amplitude  clo-
    sures  from  100% are an indication of amplitude loss on long baselines,
    due to phase decorrelation during the time averaging. The fit then shows
    strong  systematic errors; if this occurs, baseline based calibration of
    the amplitudes might be preferred.

    Option /PLOT will plot the fitted curve over  the  data.  Option  /RESET
    will reset the calibration curve in memory.

    Fitted curves may be of two kinds:

      -  Cubic splines (the default).  By default knots are regularly spaced
        with an interval between knots set by the SET STEP  command.   Addi-
        tional  knots  may  be  introduced with the option "/BREAK kind time
        [kind time ...]"  which  introduces  a  break  at  abscissa  'time';
        'kind'  is an integer in the range 0-3; 0 means that a discontinuity
        will be present, 1 that the first derivative will be  discontinuous,
        and  so  on.  Several breaks may be introduced. The program will de-
        tect an error if too many breaks are  introduced,  compared  to  the
        density of data points.

      -  Polynomial  curves  may  be  used instead.  For this the option is:
        /POLYNOMIAL [degree] indicating the degree of  the  polynomial  (de-
        fault 0).

    Normally  the  data points are all assigned the same weight for the fit.
    With option /WEIGHT, the data points are weighted according to their er-
    rors.


Gildas manager 2022-01-17