The user needs to define interactively:
♦ A factor
♦ An “area” of the matrix over which the factor is to be applied
where the area to be factored is defined via the SELECT procedures - see 10.6. Note that the “area” may actually be defined in terms of cell values so that it need not be a “block” of cells.
By default the selected area to be factored will be the entire matrix, so that in the case of a stacked matrix all levels are included by default.
However a “short cut” select procedure may also be used with stacked matrices whereby a single square “level” and/or “block” of the full matrix is directly pre-selected to be factored, as opposed to the more long-winded but equivalent process of explicitly identifying the row and column limits associated with a specific level/block. Note that having nominated a particular sub-matrix the selection may be further refined by setting, e.g., internal zone limits and/or cell value conditions as “AND” conditions.
Note that a single level may equally be selected for factoring using the LEVEL parameter in the batch file MXFACTOR; see 10.20.3.