2016 Update

Task/Identity-matrix/00DESCRIPTION

@@ -1,7 +1,11 @@
-Build an [[wp:identity matrix|identity matrix]] of a size known at runtime.
+;Task:
+Build an   [[wp:identity matrix|identity matrix]]   of a size known at run-time.
+
+
+An ''identity matrix'' is a square matrix of size '''''n'' × ''n''''',
+<br>where the diagonal elements are all '''1'''s (ones),
+<br>and all the other elements are all '''0'''s (zeroes).
 
-An identity matrix is a square matrix, of size ''n'' &times; ''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      \\
@@ -10,3 +14,10 @@ where the diagonal elements are all 1s, and the other elements are all 0s.
   \vdots & \vdots & \vdots & \ddots & \vdots \\
   0      & 0      & 0      & \cdots & 1      \\
 \end{bmatrix}</math>
+
+
+;Related tasks:
+* &nbsp; [[Spiral matrix]]
+* &nbsp; [[Zig-zag matrix]]
+* &nbsp; [[Ulam_spiral_(for_primes)]]
+<br><br>

Task/Identity-matrix/ALGOL-W/identity-matrix.alg

@@ -0,0 +1,22 @@
+begin
+    % set m to an identity matrix of size s                                  %
+    procedure makeIdentity( real    array m ( *, * )
+                          ; integer value s
+                          ) ;
+        for i := 1 until s do begin
+            for j := 1 until s do m( i, j ) := 0.0;
+            m( i, i ) := 1.0
+        end makeIdentity ;
+
+    % test the makeIdentity procedure                                        %
+    begin
+        real array id5( 1 :: 5, 1 :: 5 );
+        makeIdentity( id5, 5 );
+        r_format := "A"; r_w := 6; r_d := 1; % set output format for reals   %
+        for i := 1 until 5 do begin
+            write();
+            for j := 1 until 5 do writeon( id5( i, j ) )
+        end for_i ;
+    end text
+
+end.

Task/Identity-matrix/AppleScript/identity-matrix.applescript

@@ -0,0 +1,77 @@
+-- idMatrix :: Int -> [(0|1)]
+on idMatrix(n)
+    set xs to range(1, n)
+
+    script row
+        on lambda(x)
+            script zeroOrOne
+                on lambda(i)
+                    cond(i = x, 1, 0)
+                end lambda
+            end script
+
+            map(zeroOrOne, xs)
+        end lambda
+    end script
+
+    map(row, xs)
+end idMatrix
+
+
+-- TEST
+on run
+
+    idMatrix(5)
+
+end run
+
+
+
+-- GENERIC FUNCTIONS ------------------------------------------
+
+-- map :: (a -> b) -> [a] -> [b]
+on map(f, xs)
+    tell mReturn(f)
+        set lng to length of xs
+        set lst to {}
+        repeat with i from 1 to lng
+            set end of lst to lambda(item i of xs, i, xs)
+        end repeat
+        return lst
+    end tell
+end map
+
+-- Lift 2nd class handler function into 1st class script wrapper
+-- mReturn :: Handler -> Script
+on mReturn(f)
+    if class of f is script then
+        f
+    else
+        script
+            property lambda : f
+        end script
+    end if
+end mReturn
+
+-- cond :: Bool -> a -> a -> a
+on cond(bool, f, g)
+    if bool then
+        f
+    else
+        g
+    end if
+end cond
+
+-- range :: Int -> Int -> [Int]
+on range(m, n)
+    if n < m then
+        set d to -1
+    else
+        set d to 1
+    end if
+    set lst to {}
+    repeat with i from m to n by d
+        set end of lst to i
+    end repeat
+    return lst
+end range

Task/Identity-matrix/Elena/identity-matrix.elena

@@ -0,0 +1,14 @@
+#import system.
+#import extensions.
+#import system'routines.
+#import system'collections.
+
+#symbol program=
+[
+    #var n := console write:"Enter the matrix size:" readLine toInt.
+
+    #var identity := n repeat &each: i = [ n repeat &each: j = [ (i == j)iif:1:0 ] summarize:(ArrayList new) ] summarize:(ArrayList new).
+
+    identity run &each:
+        row = [ console writeLine:row ].
+].

Task/Identity-matrix/Fortran/identity-matrix-3.f

@@ -0,0 +1,3 @@
+      DO 1 I = 1,N
+        DO 1 J = 1,N
+    1     A(I,J) = (I/J)*(J/I)

Task/Identity-matrix/Java/identity-matrix.java

@@ -1,30 +1,13 @@
-public class IdentityMatrix {
+public class PrintIdentityMatrix {
 
-	public static int[][] matrix(int n){
-		int[][] array = new int[n][n];
-		
-		for(int row=0; row<n; row++){
-			for(int col=0; col<n; col++){
-				if(row == col){
-					array[row][col] = 1;
-				}
-				else{
-					array[row][col] = 0;
-				}
-			}
-		}
-		return array;
-	}
-	public static void printMatrix(int[][] array){
-		for(int row=0; row<array.length; row++){
-			for(int col=0; col<array[row].length; col++){
-				System.out.print(array[row][col] + "\t");
-			}
-			System.out.println();
-		}
-	}
-	public static void main (String []args){
-		printMatrix(matrix(5));
-	}
+    public static void main(String[] args) {
+        int n = 5;
+        int[][] array = new int[n][n];
+
+        IntStream.range(0, n).forEach(i -> array[i][i] = 1);
+
+        Arrays.stream(array)
+                .map((int[] a) -> Arrays.toString(a))
+                .forEach(System.out::println);
+    }
 }
-By Sani Yusuf @saniyusuf.

Task/Identity-matrix/JavaScript/identity-matrix-1.js

@@ -0,0 +1,8 @@
+function idMatrix(n) {
+    return Array.apply(null, new Array(n))
+        .map(function (x, i, xs) {
+            return xs.map(function (_, k) {
+                return i === k ? 1 : 0;
+            })
+        });
+}

Task/Identity-matrix/JavaScript/identity-matrix-2.js

@@ -0,0 +1,13 @@
+(() => {
+
+    // idMatrix :: Int -> [[0 | 1]]
+    const idMatrix = n => Array.from({
+            length: n
+        }, (_, i) => Array.from({
+            length: n
+        }, (_, j) => i !== j ? 0 : 1));
+
+
+    // TEST
+    return idMatrix(5);
+})();

Task/Identity-matrix/JavaScript/identity-matrix-3.js

@@ -0,0 +1,2 @@
+[[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]]

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

@@ -1,3 +0,0 @@
-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

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

Task/Identity-matrix/PowerShell/identity-matrix-1.psh

@@ -1,21 +1,17 @@
-function id($n) {
-    if($n -gt 0) {
-        $array = @(1..$n | foreach{ @(0) })
-        0..($n-1) | foreach{
-            $i = $_
-            $array[$i] = @(switch(0..($n-1)){
-                $i {1}
-                default {0}
-            })
+function identity($n) {
+    if(0 -lt $n) {
+        $array = @(0) * $n
+        foreach ($i in 0..($n-1)) {
+            $array[$i] = @(0) * $n
+            $array[$i][$i] = 1
         }
         $array
     } else { @() }
 }
 function show($a) {
-    if($a.Count -gt 0) {
-        $n = $a.Count - 1
-        0..$n | foreach{ "$($a[$_][0..$n])" }
+    if($a) {
+        0..($a.Count - 1) | foreach{ if($a[$_]){"$($a[$_])"}else{""} }
     }
 }
-$array = id 4
+$array = identity 4
 show $array

Task/Identity-matrix/R/identity-matrix-2.r

@@ -1,4 +1,7 @@
-     [,1] [,2] [,3]
-[1,]    1    0    0
-[2,]    0    1    0
-[3,]    0    0    1
+Identity_matrix=function(size){
+  x=matrix(0,size,size)
+  for (i in 1:size) {
+    x[i,i]=1
+  }
+  return(x)
+}

Task/Identity-matrix/R/identity-matrix.r

@@ -1 +0,0 @@
-diag(3)

Task/Identity-matrix/VBScript/identity-matrix-2.vb

@@ -0,0 +1,15 @@
+n = 8
+
+arr = Identity(n)
+
+for i = 0 to n-1
+    for j = 0 to n-1
+        wscript.stdout.Write arr(i,j) & " "
+    next
+    wscript.stdout.writeline
+next
+
+Function Identity (size)
+    Execute Replace("dim a(#,#):for i=0 to #:for j=0 to #:a(i,j)=0:next:a(i,i)=1:next","#",size-1)
+    Identity = a
+End Function

Task/Identity-matrix/Vala/identity-matrix.vala

@@ -0,0 +1,25 @@
+int main (string[] args) {
+	if (args.length < 2) {
+		print ("Please, input an integer > 0.\n");
+		return 0;
+	}
+	var n = int.parse (args[1]);
+	if (n <= 0) {
+		print ("Please, input an integer > 0.\n");
+		return 0;
+	}
+	int[,] array = new int[n, n];
+	for (var i = 0; i < n; i ++) {
+		for (var j = 0; j < n; j ++) {
+			if (i == j) array[i,j] = 1;
+			else array[i,j] = 0;
+		}
+	}
+	for (var i = 0; i < n; i ++) {
+		for (var j = 0; j < n; j ++) {
+			print ("%d ", array[i,j]);
+		}
+		print ("\b\n");
+	}
+	return 0;
+}