Just another update

Task/Identity-matrix/00DESCRIPTION

@@ -1,4 +1,7 @@
-Build an [[wp:identity matrix|identity matrix]] of a size known at runtime. An identity matrix is a square matrix, of size ''n'' × ''n'', where the diagonal elements are all 1s, and the other elements are all 0s.
+Build an [[wp:identity matrix|identity matrix]] of a size known at runtime.
+
+An identity matrix is a square matrix, of size ''n'' × ''n'',
+where the diagonal elements are all 1s, and the other elements are all 0s.
 
 <math>I_n = \begin{bmatrix}
   1      & 0      & 0      & \cdots & 0      \\

Task/Identity-matrix/ATS/identity-matrix.ats

@@ -0,0 +1,33 @@
+(* ****** ****** *)
+//
+// How to compile:
+//
+// patscc -DATS_MEMALLOC_LIBC -o idmatrix idmatrix.dats
+//
+(* ****** ****** *)
+//
+#include
+"share/atspre_staload.hats"
+//
+(* ****** ****** *)
+
+extern
+fun
+idmatrix{n:nat}(n: size_t(n)): matrixref(int, n, n)
+implement
+idmatrix(n) =
+matrixref_tabulate_cloref<int> (n, n, lam(i, j) => bool2int0(i = j))
+
+(* ****** ****** *)
+
+implement
+main0 () =
+{
+//
+val N = 5
+//
+val M = idmatrix(i2sz(N))
+val () = fprint_matrixref_sep (stdout_ref, M, i2sz(N), i2sz(N), " ", "\n")
+val () = fprint_newline (stdout_ref)
+//
+} (* end of [main0] *)

Task/Identity-matrix/Eiffel/identity-matrix.e

@@ -0,0 +1,61 @@
+class
+	APPLICATION
+
+inherit
+	ARGUMENTS
+
+create
+	make
+
+feature {NONE} -- Initialization
+
+	make
+			-- Run application.
+		local
+		    dim : INTEGER -- Dimension of the identity matrix
+		do
+		    from dim := 1 until dim > 10 loop
+		    	print_matrix( identity_matrix(dim) )
+				dim := dim + 1
+				io.new_line
+			end
+
+		end
+
+feature -- Access
+
+	identity_matrix(dim : INTEGER) : ARRAY2[REAL_64]
+
+		require
+			dim > 0
+		local
+			matrix : ARRAY2[REAL_64]
+			i : INTEGER
+		do
+
+			create matrix.make_filled (0.0, dim, dim)
+			from i := 1 until i > dim loop
+				matrix.put(1.0, i, i)
+				i := i + 1
+			end
+
+			Result := matrix
+		end
+
+	print_matrix(matrix : ARRAY2[REAL_64])
+		local
+			i, j : INTEGER
+		do
+			from i := 1 until i > matrix.height loop
+				print("[ ")
+				from j := 1 until j > matrix.width loop
+					print(matrix.item (i, j))
+					print(" ")
+					j := j + 1
+				end
+				print("]%N")
+				i := i + 1
+			end
+		end
+
+end

Task/Identity-matrix/JavaScript/identity-matrix.js

@@ -0,0 +1,3 @@
+function im(n) {
+    return Array.apply(null, new Array(n)).map(function(x, i, a) { return a.map(function(y, k) { return i === k ? 1 : 0; }) });
+}

Task/Identity-matrix/Perl-6/identity-matrix-3.pl6

@@ -0,0 +1,3 @@
+sub identity-matrix($n) {
+    [1, 0 xx $n-1], *.rotate(-1).item ... *[*-1] == 1
+}

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

Task/Identity-matrix/Ruby/identity-matrix-2.rb

@@ -0,0 +1,4 @@
+2.1.1 :001 > require "matrix"
+ => true
+2.1.1 :002 > Matrix.identity(5)
+ => Matrix[[1, 0, 0, 0, 0], [0, 1, 0, 0, 0], [0, 0, 1, 0, 0], [0, 0, 0, 1, 0], [0, 0, 0, 0, 1]]