[erlang-questions] power(N,P), cant get it to work

[Circular Function]

-module(math).
-export([fac/1, sq/1,cube/1,power/2]).

fac(N) when N>0 ->
        N * fac(N-1);
fac(0) ->
        1.
    
sq(X) -> X*X.

cube(X) -> X*X*X.

power(N,P) ->
        if P==0 ->
                1;
        true ->
                if P>0 ->
                        N * power(N,P - 1);
                true ->
                        1 / power(N,-1 * P).


Erlang (BEAM) emulator version 5.6.2 [async-threads:0]

Eshell V5.6.2  (abort with ^G)
1> c(math).
../math.erl:20: syntax error before: '.'
../math.erl:2: function power/2 undefined
error
2> 


am i using the "true ->" correctly? it is like else right?



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