rate_dataset::form_ratio

Source: dataset/rate/rate_dataset__form_ratio.pro

  rate_dataset::form_ratio
        Forms a ratio between two previously plotted streams, and adds
        them as a new stream to the dataset.

 Usage:
        dsref -> form_ratio,index1,index2

 Arguments:
        index1  int     input   The index of the numerator stream in the ratio
        index2  int     input   The index of the denominator stream in
                                the ratio

 Keywords:
        ratio           If set, then form the ratio of the 2 streams (default
                        action).
        difference      If set, then form the difference between the streams.
        product         If set, then form the product of the 2 streams.
        sum             If set, then form the sum of the 2 streams
        inverse         If set, then form the inverse of the first
                        stream (the second stream is ignored).
        power           If set, then raise stream to a power
        operation string The symbolic operation to perform.
        scalar  any     input   If this keyword is present, then the
                                second stream is ignored and the
                                supplied scalar value is used, on the
                                right of the operand.

 Notes:
        Only one operand keyword may be given. If the inverse or the
        scalar keys are given, then the second argument is ignored (if
        both are given the scalar is ignored as well).

 History:
        Original version, derived from extract_sect: 8/11/91; SJT
        Add capability for more than a single ratio: 2/3/92; SJT
        Add option to form ratio for specific sectors: 17/9/92; SJT
        Set sector_flag if extracting sectors: 5/11/92; SJT
        Cope with dual accumulation MFSA rates: 6/11/92; SJT
        Clean up case of sector ratios when only 1 channel present:
                                                12/5/93; SJT
        Add option to use average sectors as well: 28/3/95; SJT
        Make a rate_dataset method: ??/??/00; SJT
        Add options to do sums, products etc: 27/6/01; SJT
        Add power operation: 15/4/02; SJT