Practice Assignment for Future Learn Functional Programming with Erlang Course.

week2_assignment.erl

-module(assignment).
-export([perimeter/1,area/1,bits/1,tests/0]).

%Perimeter functions for circle,rectangle, square
perimeter({circle, {_X,_Y}, R}) ->
    2*math:pi()*R;
perimeter({rectangle,H,W}) ->
    2*H + 2*W;
perimeter({square,L}) ->
    math:pow(L,2);

%Perimeter of right triangle and triangle
perimeter({right_triangle,A,B}) ->
    A + B + math:sqrt(math:pow(A,2) + math:pow(B,2)); %calculating the hypotenuse
perimeter({triangle,A,B,C}) ->
    case is_valid(A,B,C) of %check if triangle is valid
        false ->
            io:format("Invalid Triangle");
        true ->
            A+B+C
    end.
% Area of right triangle and simple triangle
area({right_triangle,A,B}) ->
    A*B/2;
area({triangle,A,B,C}) ->
    case is_valid(A,B,C) of %check if triangle is valid
        false ->
            io:format("Invalid Triangle");
        true ->
            S = (A+B+C)/2,
            math:sqrt(S*(S-A)*(S-B)*(S-C))
    end.
%function to check validity of triangle
is_valid(A,B,C) when A+B>C, B+C>A, C+A>B ->
    true;
is_valid(_A,_B,_C) ->
    false.

% Tail recursive definition for converting to binary
convert_to_binary(0,List) ->
    List;
convert_to_binary(N,List) when N>0 -> 
    R = N rem 2,
    convert_to_binary(N div 2,[R|List]).

convert_to_binary(N) ->
    convert_to_binary(N, []).
% using the sum function of lists module to sum the integers in the list
bits(N) ->
    lists:sum(convert_to_binary(N)).

test_bits() ->
    2 = bits(3),
    3 = bits(7),
    1 = bits(8),
    pass.

test_perimeter() ->
    31.41592653589793 = perimeter({circle, {0,0}, 5}),
    22 = perimeter({rectangle,6,5}),
    25.0 = perimeter({square, 5}),
    12.0 = perimeter({right_triangle, 3,4}),
    12 = perimeter({triangle,3,4,5}),
    pass.

test_area() ->
    6.0 = area({right_triangle,3,4}),
    6.0 = area({triangle,3,4,5}),
    pass.

tests() ->
    pass = test_perimeter(),
    pass = test_area(),
    pass = test_bits(),
    pass.