` Sieve of Eratosthenes
`	Really a test of the FreeRAM features.

"Sieve of Eratosthenes"#
"Upper limit to test to ? " ? = L

"Zeroing array"#

` Set array to TRUE
`    Everything is prime until proven otherwise...

0=C 1[
  1 = !C 
  C + 1 = C
  - L ]

"Done."

` Preset a few known ones...

  0 = C 0 = !C	` 0 is not prime
  1 = C 0 = !C	` Neither is 1.

  L ;Q = M	` Test up to the square root of our upper bound

  ;S
  ;P

  _

` P: Print the array

(P
  0 = C 1[
    C % 72 [ \ # 0]
    !C [ "*" \ "." 0]
    C + 1 = C
  - L ]
  #
)


` S: Sift through the array looking for Primes

(S
  1 = P		` Start at 1

  1[
    P + 1 = P	` This is the next potential Prime.

    ` Loop until we find the next Prime

    1[
      !P	` Fetch flag
      }		` If TRUE then break-out
      P + 1 = P	` Next candidate
      P > M [ ) ]	` End? Return.
    1]		` Loop

    P ;X
  1]
    
)

` X: Strike out all the multiples of the current target

(X
  = F + F = J
  [ 
    0 = !J
    J + F = J
    < L
  ]
)





` Integer Square root
`    Herons Method
` Uses S
` Uses but preserves X and Y.

(Q
  = S
  > 2 [ \ S ) ]
  X,Y,
  S / 2 = X
  S / X + X / 2 = Y
  1[
    Y = X
    S / X + X / 2 = Y
    Y < X ]
  X = S
  '=Y '=X S
)