# Recursive Library by Guy Walker
# www.logoarts.co.uk

to add :i :j
  # return sum of two input numbers
  If :I = 0 [Output :J] [Output Add :I-1 :J+1]
end

to factorial :n
  # return factorial of N
  If :N = 1 [Output 1] [Output :N * Factorial :N-1]
end

to fib :n
  # return Nth Fibonacci number
  If :N < 2 [Output :N] [Output (Fib :N-1) + Fib :N-2]
end

to hcf :i :j
  # return highest common factor of two integers
  LocalMake "Rem Modulo :I :J
  If :Rem = 0 [Output :J] [Output HCF :J :Rem]
End

to lcm :i :j
  # return lowest common multiple of two integers
  Output :I*:J / HCF :I :J
end

to sum1ton :n
  # return sum of integers 1 to N
  If :N < 1 [Output 0] [Output :N+ Sum1toN :N-1]
end