MATLAB阶乘

function result = factorial_recursion(n)
    if n == 0 || n == 1
        result = 1;
    else
        result = n * factorial_recursion(n-1);
    end
end

>> factorial_recursion(5)
ans =
   120

function result = factorial_loop(n)
    result = 1;
    for i = 1:n
        result = result * i;
    end
end

>> factorial_loop(5)
ans =
   120

function result = factorial_builtin(n)
    result = prod(1:n);
end

>> factorial_builtin(5)
ans =
   120

function result = factorial_builtin(n)
    result = factorial(n);
end

>> factorial_builtin(5)
ans =
   120

n = 20;

% 递归方法
tic;
factorial_recursion(n);
recursion_time = toc;

% 循环方法
tic;
factorial_loop(n);
loop_time = toc;

% 内置函数方法
tic;
factorial_builtin(n);
builtin_time = toc;

>> recursion_time
recursion_time =
   0.005120604

>> loop_time
loop_time =
   3.433227e-05

>> builtin_time
builtin_time =
   1.191702e-05