# Factorial without the Command

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Sophie Culhane on 17 Sep 2020
I am struggling to figure out how to compute a factorial without the use of the command. My task is to input a nonnegative integer and have the program compute its factorial.
Here is what I have for my script so far.
function Factorial = ex1(n)
%
%
if n = 0
Factorial = 1;
elseif n >= 1
Factorial = n(n-1)(n-2)(n-3)(3)(2)(1);
end
This program does not run, however I do not know where to go from here.

James Tursa on 17 Sep 2020
Edited: James Tursa on 17 Sep 2020
You could use either use a loop to multiply all of the numbers from 1 to n, or use recursion to multiply n by the factorial of n-1 (with some method of stopping the recursion). Were you instructed to use one of these methods? You could also use some different MATLAB functions for this, but I am not sure which ones would be allowed for your homework.

#### 1 Comment

Sophie Culhane on 17 Sep 2020
We are only allowed to use very basic commands. (this includes if construct, and the while loop)

function f = Factorial(n)
%
%
if n = 0 || n = 1
f = 1;
elseif n >= 1
f = n * Factorial(n-1);
end

#### 1 Comment

Rik on 17 Sep 2020
Why did you post this answer? Direct answers without an explanation encourages cheating.
If you don't respond I will delete this answer.

William on 17 Sep 2020
function f = Factorial(n)
%
if n = 0 || n = 1
f = 1;
elseif n >= 1
a = 1:n;
f = prod(a);
end

Show 1 older comment
I didn't seem to be an assignment. Also, some parts were ready and correct.
I have seen some answers from you with similar conditions:
Rik on 17 Sep 2020
A comment posted after you posted your answer confirmed my suspicion. If you thought this wasn't a homework assignment, why didn't you post the best solution: using the built-in factorial function.
The link you posted did not look like homework to me, although I see how it might be. That user also showed willingness to put in their own effort, and they posted that a hint would also suffice. If that one is a homework question, it is a complex one, and getting help here is a valid strategy.
I would question the usefulness of posting several answers on what is obviously a homework question, if only because the OP has posted a statement to that effect.
I have the option to delete answers, but I chose to not use it if there is at least the suggestion that reasonable people might disagree. If you actually think it isn't a homework question, then you should at least try to answer the question such that you use optimal code.
PS I'll probably move your comment and this one to your answer, because that is what we are discussing.
From the initial code, I thoughed that he wants to use a recursive function. So I modified the second part of the code. Later after seeing your comment and the code of the others, I noticed that he wants to use basic operations. That's all I did and thank you for your comment about being more carefull.

Using only basic operations:
function f = Factorial(n)
%
% initial value, 0! and 1!
f = 1;
if n > 1
for i=2:n
f = f * i;
end
end

#### 1 Comment

Stephen Cobeldick on 17 Sep 2020
The if statement is superfluous: that for loop will only iterate for n>=2 anyway.