A-M baby

Task/Matrix-multiplication/REXX/matrix-multiplication.rexx

@@ -0,0 +1,37 @@
+/*REXX program multiplies two matrixes together, shows matrixes & result*/
+x.=
+x.1 = '1 2'
+x.2 = '3 4'
+x.3 = "5 6"                            /*either kind of quote works.    */
+x.4 = '7 8'
+            do   r=1 while x.r\==''    /*build the "A" matric from X. #s*/
+              do c=1 while x.r\=='';   parse var x.r a.r.c x.r;    end
+            end
+Arows=r-1;  Acols=c-1
+y.=
+y.1 =  1 2 3                           /*if all values are positive,    */
+y.2 =  4 5 6                           /*can eliminate the quotes.      */
+              do   r=1 while y.r\==''  /*build the "B" matric from Y. #s*/
+                do c=1 while y.r\=='';    parse var y.r b.r.c y.r;    end
+              end
+Brows=r-1;  Bcols=c-1
+c.=0; L=0                              /*L  is max width of an element. */
+           do i        =1 for Arows    /*multiply matrix  A & B  ──<E29480>  C */
+               do j    =1 for Bcols
+                   do k=1 for Acols
+                   c.i.j = c.i.j + a.i.k * b.k.j;   L=max(L,length(c.i.j))
+                   end   /*k*/
+               end       /*j*/
+           end           /*i*/
+
+call showMat  'A', Arows, Acols
+call showMat  'B', Brows, Bcols
+call showMat  'C', Arows, Bcols
+exit                                   /*stick a fork in it, we're done.*/
+/*──────────────────────────────────SHOWMAT subroutine──────────────────*/
+showMat:  parse arg mat,rows,cols;   say
+say center(mat 'matrix',cols*(L+1)+4,"─")
+       do r    =1 for rows; _=
+           do c=1 for cols; _=_ right(value(mat'.'r'.'c),L); end;    say _
+       end
+return