In work with input-output analysis, one frequently needs to balance a table to known row and column totals. Three methods of scaling are offered in *G7*: ordinary RAS, proportional scaling RAS (*psras*), and right-direction RAS (*rdras*). In additional, outside information may be imposed using the “precondition” features described below.

The RAS commands are:

**ras|psras|rdras [<-f|c>] <matrix>[(r rgroup)][(c cgroup)]<rowctrl><colctrl> [yr][r|c][-maxiter][-precon] [-tolerance]**where:

-f|c: specifies the flow (default) or the coefficient mode, ras|psras|rdras: specifies the method of scaling to be used, matrix: is the name of the matrix whose elements are to be balanced, (r rgroup): (c cgroup): are options that determine which rows and columns are included, rowctrl: colctrl: are vectors that contain the row and column totals, yr: optionally specifies the year for which the matrix is to be balanced. If a year is not specified, the matrix is balanced over the period specified by the current *fdates*.r|c: optionally specifies whether the sum of the row totals or the sum of the column totals controls the calculations if the two are not the same. -maxiter: optionally determines maximum number of iterations. The default is 100. -precon: optionally specifies that name of a file containing the preconditions that are to be imposed. -tolerance: optionally specifies the tolerance for the convergence test. The default value is 0.000002.

If one or more of row and/or column totals are questionable, the matrix still may be balanced by a special use of proportional scaling RAS, which is explained in Balancing Matrices with Uncertain Totals.