I have a problem where my code works on matlab but does not on matlab grader could there be some type of reason for this.

function y = mysum(n)
n=input('Enter an integer');
 
sum=0;
if n<0 
    y=-1;
    disp('cannot input a negative number');
else for i=0:n
        sum=sum+i;
end
        y=sum;
end

here is my code it works for matlab but nor grader please help.

Answer 1

[Image Analyst]

In addition to what Walter said, don't use "sum" as the name of your variable since it's a built-in function. And use k instead of i since sometimes we use i for the imaginary variable. Some corrections:

% Script to call the function for some n's.
for k = -1 : 3
	fprintf('For n = %d, mysum(%d) = %d.\n', k, k, mysum(k));
end

%================================================================
function y = mysum(n)
y = 0;
if n < 0
	y = -1;
	errorMessage = sprintf('You cannot input a negative number, like %d', n)
	uiwait(errordlg(errorMessage));
else
	for k = 0 : n
		y = y + k;
	end
end
end

Answer 2

[Walter Roberson]

You should not be using input() there. The user should be passing the value of n when they invoke the function.

It would not be entirely unreasonable to use

function y = mysum(n)
   if nargin < 1
     n = input('Enter an integer');
   end