
   To multiply two matrices you must first declare iteration variables and
   multidimensional labels.  The matrix elements are multiplied using the
   %SUM% statement.  E. g.

   þLABEL A[1..3,1..3], B[1..3,1..3], C[1..3,1..3]
   þITERATE I FROM 1 TO 3
   þITERATE J FROM 1 TO 3
   þITERATE K FROM 1 TO 3
   .
   .          Expressions are defined for each components of the
   .          matrix labels A, and B.

   þC[I,J]:=SUM(K) A[I,K]*B[K,J]   
                                                                       
              The resulting matrix, C, is the matrix product of A and
              B.
