
   Syntax       label %:= SUM(%&iteration&{%,%&iteration&%,%...}%)% expression

   Purpose      Sums expressions on &iteration&.

   Note         This command is primarily used for tensor manipulation e.g.
                matrix and vector multiplication.

   %Example%
   þLABEL U[1..2], A[1..2,1..2], V[1..2,1..2]
   þITERATE I FROM 1 TO 2
   þITERATE J FROM 1 TO 2
   þV[I] : v[I]
   þA[I,J] : a[I,J]
   þU[I]:=SUM(J) A[I,J]*V[J]

   PROCEDURE Example(INTEGER N ; LABEL U,A,V) ;
     ITERATE I FROM 1 TO N ;
     ITERATE J FROM 1 TO N ;
     U[I]:=SUM(J) A[I,J]*V[J] ;
   EXIT
