Tail call recursion - Fibonacci

gistfile1.txt

# tail call optimization
RubyVM::InstructionSequence.compile_option = {:tailcall_optimization => true,:trace_instruction => false}

# Fibonacci sequence
def fib(n,tail,tail2)
  return 1 if n == 1
  return 1 if n == 2
  return tail + tail2 if n == 3
  fib(n-1, tail2, tail+tail2)
end

# fib(100,1,1)

# Sum of the first elements of the Fibonacci sequence
def f(n,t1,t2,t3)
  return 1 if n == 1
  return 2 if n == 2
  return t1+t2+t3 if n == 3
  t=t1+t2
  f(n-1, t2, t, t+t3)
end

# f(100,1,1,2)