Magic squares of doubly even order: Difference between revisions

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 </pre>
-=={{header|zkl}}==
+=={{header|Ruby}}==
-{{trans|Java}}
-<lang zkl>class MagicSquareDoublyEven{
-   fcn init(n){ var result=magicSquareDoublyEven(n) }
-   fcn toString{
-      sink,n:=Sink(String),result.len();  // num collumns
-      fmt:="%2s ";
-      foreach row in (result)
-         { sink.write(row.apply('wrap(n){ fmt.fmt(n) }).concat(),"\n") }
-      sink.write("\nMagic constant: %d".fmt((n*n + 1)*n/2));
-      sink.close();
-   }
-   fcn magicSquareDoublyEven(n){
-      if (n<4 or n%4!=0 or n>16)
-	 throw(Exception.ValueError("base must be a positive multiple of 4"));
-      bits,size,mult:=0b1001011001101001, n*n, n/4;
-      result:=n.pump(List(),n.pump(List(),0).copy);  // array[n,n] of zero
+<lang ruby>def double_even_magic_square(n)
-      foreach i in (size){
+  raise ArgumentError, "Need multiple of four" if n%4 > 0
-	 bitsPos:=(i%n)/mult + (i/(n*mult)*4);
+  block_size, max = n/4, n*n
-	 value:=(bits.bitAnd((2).pow(bitsPos))) and i+1 or size-i;
+  pre_pat = [true, false, false, true,
-	 result[i/n][i%n]=value;
+             false, true, true, false]
-      }
+  pre_pat += pre_pat.reverse
-      result;
+  pattern = pre_pat.flat_map{|b| [b] * block_size} * block_size
-   }
+  flat_ar = pattern.each_with_index.map{|yes, num| yes ? num+1 : max-num}
-}
+  flat_ar.each_slice(n).to_a
-MagicSquareDoublyEven(8).println();</lang>
+end
+def to_string(square)
+  n = square.size
+  fmt = "%#{(n*n).to_s.size + 1}d" * n
+  square.inject(""){|str,row| str << fmt % row << "\n"}
+end
+puts to_string(double_even_magic_square(8))</lang>
 {{out}}
 <pre>
 2 62 61 60 59  7  8
-10 54 53 52 51 15 16
+55 11 12 13 14 50 49
 47 19 20 21 22 42 41
-39 27 28 29 30 34 33
+26 38 37 36 35 31 32
-31 35 36 37 38 26 25
+34 30 29 28 27 39 40
 23 43 44 45 46 18 17
-50 14 13 12 11 55 56
+15 51 52 53 54 10  9
 58  6  5  4  3 63 64
-Magic constant: 260
 </pre>