超简单的Erlang复数实现-优快云博客

本文介绍了一个用Erlang实现复数运算的简单模块，包括加法、减法、乘法和除法等基本运算，并提供了获取实部和虚部的方法。

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% 超简单的复数的Erlang实现
% 参见: http://www.trapexit.org/Complex_Numbers
-module(complex).
-export([make/2, is_complex/1, add/2, sub/2, mult/2, divide/2,
         get_real/1, get_imaginary/1]).
-record( complex, {real, imaginary}).
is_complex(X) when is_record(X, complex) -> true;
is_complex(_) -> false.
make(Real, Imaginary) ->
    #complex{real = Real, imaginary = Imaginary}.
make(X) when is_record(X, complex) -> X;
make(Real) -> make(Real, 0).
add(X, Y) ->
    A = make(X), B = make(Y),
    make( A#complex.real      + B#complex.real,
          A#complex.imaginary + B#complex.imaginary).
sub(X, Y) ->
    A = make(X), B = make(Y),
    make( A#complex.real      - A#complex.real,
          B#complex.imaginary - B#complex.imaginary).
mult(X, Y) ->
    A = make(X), B = make(Y),
    make( (A#complex.real * B#complex.real)
              - (A#complex.imaginary * B#complex.imaginary),
          (A#complex.real * B#complex.imaginary)
              + (B#complex.real * A#complex.imaginary) ).
divide(X,Y) ->
    A = make(X), B = make(Y),
    Divisor = math:pow(B#complex.real,2) + math:pow(B#complex.imaginary,2),
    make( ((A#complex.real * B#complex.real)
            + (A#complex.imaginary * B#complex.imaginary)) / Divisor,
          ((A#complex.imaginary * B#complex.real)
            - (A#complex.real * B#complex.imaginary)) / Divisor).
get_real(X) -> X#complex.real.
get_imaginary(X) -> X#complex.imaginary.