30-Dec-2022 14:58:22

ulam_spiral_test():
  MATLAB/Octave version 4.2.2
  Test ulam_spiral()

spiral_array_test():
  spiral_array(thick,k) makes a 2*thick+1 order array S
  of integers, spiralling out from a central value of k.

  thick = 3
  k = 1
  S:
   37   36   35   34   33   32   31
   38   17   16   15   14   13   30
   39   18    5    4    3   12   29
   40   19    6    1    2   11   28
   41   20    7    8    9   10   27
   42   21   22   23   24   25   26
   43   44   45   46   47   48   49

prime_spiral_test():
  prime_spiral(thick,k) makes a 2*thick+1 order array P
  of 1's for primes and 0's otherwise,
  spiralling out from a central value of k.

  thick = 3
  k = 1
  P:
  1  0  0  0  0  0  1
  0  1  0  0  0  1  0
  0  0  1  0  1  0  1
  0  1  0  0  1  1  0
  1  0  1  0  0  0  0
  0  0  0  1  0  0  0
  1  0  0  0  1  0  0

  thick = 30
  k = 1
  P:
  Graphics saved as "prime_spiral.png"

ulam_spiral_test():
  Normal end of execution.

30-Dec-2022 14:58:25