Just another update

Task/Identity-matrix/REXX/identity-matrix-1.rexx

@@ -1,28 +1,33 @@
-/*REXX program to  create  and  display  an identity matrix.            */
-call identity_matrix 4                 /*build and display a 4x4 matrix.*/
-call identity_matrix 5                 /*build and display a 5x5 matrix.*/
+/*REXX program  creates  and  displays  any sized  identity matrix.     */
+          do k=3  to 6                 /* [↓]  build & display a matrix.*/
+          call identity_matrix  k      /*build and display a kxk matrix.*/
+          end   /*k*/                  /* [↑]  use general─purpose disp.*/
 exit                                   /*stick a fork in it, we're done.*/
-/*─────────────────────────────────────IDENTITY_MATRIX subroutine───────*/
+/*──────────────────────────────────IDENTITY_MATRIX subroutine──────────*/
 identity_matrix:  procedure;  parse arg n;  $=
 
-    do r=1 for n                       /*build indentity matrix, by row,*/
-          do c=1 for n                 /*                    and by cow.*/
-          $=$ (r==c)                   /*append zero or one (if on diag)*/
-          end    /*c*/
-    end          /*r*/
+          do       r=1  for n          /*build identity matrix,  by row,*/
+                do c=1  for n          /*               ···  and by col.*/
+                $=$  (r==c)            /*append zero or one (if on diag)*/
+                end   /*c*/
+          end         /*r*/
 
-call showMatrix 'identity matrix of size' n,$,n
+call showMatrix  'identity matrix of size'  n,   $
 return
-/*─────────────────────────────────────TELL subroutine───&find the order*/
-showMatrix: procedure; parse arg hdr,x,order,sep;  if sep=='' then sep='═'
-    width=2          /*width of field to be used to display the elements*/
-decPlaces=1          /*# decimal places to the right of decimal point.  */
-say;  say center(hdr,max(length(hdr)+6,(width+1)*words(x)%order),sep); say
-#=0
-           do row=1      for order;   aLine=
-                do col=1 for order;   #=#+1
-                aLine=aLine  right(format(word(x,#),,decPlaces)/1, width)
-                end   /*col*/          /*dividing by 1 normalizes the #.*/
-           say aLine
-           end        /*row*/
+/*──────────────────────────────────SHOWMATRIX subroutine───────────────*/
+showMatrix: procedure; parse arg hdr,x;  #=words(x)  /*#:  # of elements*/
+dp=0                                         /*DP:   dec fraction width.*/
+w=0                                          /*W:    integer part width.*/
+      do n=1  until n*n>=#;  _=word(x,n)     /*find matrix order (size).*/
+      parse var _ y '.' f;   w=max(w, length(y));    dp=max(dp, length(f))
+      end   /*n*/      /* [↑]  idiomatically find widths to align output*/
+w=w+1
+say;  say center(hdr, max(length(hdr)+6, (w+1)*#%n), '─');  say
+#=0                                                       /*#: element #*/
+          do       row=1  for n;      _=left('',n+w)      /*indentation.*/
+                do col=1  for n;      #=#+1               /*bump element*/
+                _=_  right(format(word(x, #), , dp)/1, w)
+                end   /*col*/         /* [↑]  division by 1 normalizes #*/
+          say _                       /*display one line of the matrix. */
+          end         /*row*/
 return