Keywords: class-average

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### ACCUMULATE

            LAS\ACCUMULATE

        ACCUMULATE  is  used  to  integrate step by step an ensemble of spectra.
        The T spectrum is added to the R spectrum with the  current  weights.  R
        thus  contains  the current sum, and T the last sum. As command AVERAGE,
        ACCUMULATE checks for the positional coincidence and  calibration  homo-
        geneity according to SET MATCH and SET CALIBRATION respectively. Aligne-
        ment of spectra is checked according to SET ALIGN  command.  Accumulated
        spectra may have different spectral resolution. In this latter case, the
        final spectrum has the coarsest resolution of the two input spectra, and
        each  channel will be the weighted average of the average values of each
        spectrum in the resulting channel. It is however preferable  to  accumu-
        late spectra which have the same resolution.

        For  EQUAL  weights, ACCUMULATE computes the sum of the two spectra, al-
        lowing addition of an ensemble of spectra after division  by  the  total
        number of spectra.

        For  other  weightings, ACCUMULATE computes the average of the two spec-
        tra.

        ACCUMULATE also works on Continuum drift. The alignement may be  Channel
        or Position in this case.

Please consider that `ACCUMULATE` behaves differently if using an `EQUAL` weight or another one: this provides to the user a way to perform its own average by first adding the spectra and then dividing them at its will.