First steps in Erlang

first.erl

-module(first).
-export([double/1,treble/1,square/1,mult/2,area/3]).

mult(X,Y) ->
  X*Y.

double(X) ->
  mult(2,X).

treble(X) ->
  mult(3,X).

square(X) ->
  mult(X,X).

area(A,B,C) ->
  S = (A+B+C)/2,
  math:sqrt(S*(S-A)*(S-B)*(S-C)).

second.erl

-module(second).
-export([hypotenuse/2,perimeter/2,area/2]).

hypotenuse(A,B) ->
  H2 =first:square(A)+first:square(B),
  math:sqrt(H2).

perimeter(A,B) ->
  H =hypotenuse(A,B),
  H+A+B.

area(A,B) ->
  B*A/2.

Good job!

Thanks! Baby steps, but I'm loving the Erlang simplicity :)