Task

Produce a spiral array.



A   spiral array   is a square arrangement of the first    N2   natural numbers,   where the

numbers increase sequentially as you go around the edges of the array spiraling inwards.



For example, given   5,   produce this array:

 0  1  2  3  4
15 16 17 18  5
14 23 24 19  6
13 22 21 20  7
12 11 10  9  8



Related tasks

   Zig-zag matrix 
   Identity_matrix
   Ulam_spiral_(for_primes)


Input "Width:  ";w
Input "Height: ";h
Print
 
For i = 0 To h-1
  For j = 0 To w-1
    Print Using "__#"; FUNC(_Spiral(w,h,j,i));
  Next
  Print
Next
End
 
 
_Spiral Param(4)
If d@ Then
  Return (a@ + FUNC(_Spiral(b@-1, a@, d@ - 1, a@ - c@ - 1)))
Else
  Return (c@)
EndIf