.. index::
   single: G7 Command; ras
   single: G7 Command; psras
   single: G7 Command; rdras
   single: Preconditions (Part of RAS Command)
   single: Balancing of Matrices
   single: Sums of Matrix Columns or Rows

Matrix Balancing by the Ordinary RAS Method
===========================================
	

.. _G7UGordinaryras:

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.

Related Topics: :ref:`coef <G7RMcoef>`, :ref:`flow <G7RMflow>`, :ref:`psras <G7RMpsras>`, :ref:`rdras <G7RMrdras>`