tailrecursion.erl

untitled

-module(tailrecursion).
-export([fac/1,loop/1,sum/1,maximum/1,fib/1,perfect/1]).

fac(N) -> fac(N,1).
fac(0,P) ->
  P;
fac(N,P) when N>0 ->
  fac(N-1,P*N).

loop(N) when N>0 ->
  io:format("~p~n",[N]),
  loop(N-1);
loop(_) ->
  io:format("bye~n").

sum(N) -> sum(N,0).
sum(0,P) -> P;
sum(N,P) when N>0 ->
  sum(N-1,N+P).

maximum(N) -> maximum(N,0).
maximum(0,P) -> P;
maximum(N,P) when N>0 ->
  case N>P of
      true -> maximum(N-1,N);
      false -> maximum(N-1,P)
  end.

fib(N) ->
  fib(N,0,1).

fib(0,P,_C) ->
  P;
fib(N,P,C) ->
  fib(N-1,C,P+C).

perfect(N) ->
  perfect(N,1,0).

perfect(N,N,S) ->
  N==S;
perfect(N,M,S) when N rem M == 0 ->
  perfect(N,M+1,S+M);
perfect(N,M,S) ->
  perfect(N,M+1,S).