How do I properly use sum to sum up microstates?

Hey, I'm trying to use a function to sum up the microstates in an evenly split two configuration system but can't get my code to work. Here's what I have:

 function sumW = microstateSum(N)
 n1 = N:0;
 n2 = 0:N;
 sumW = sum(factorial(N)/(factorial(n1)*factorial(n2)));

I'm getting an error on line 5, the last line, with * telling me that matrix dimension must agree. I just want the n1 and n2 variables to decrement and increment respectively but not interpret it as matrix multiplication. I was working with a for loop but couldn't get that to work either. New to Matlab.

Answer 1

[Walter Roberson]

N:0 is length 0.

N:-1:0 would be length N+1

After that change the / to ./ and change the * to .*

[Ryan]

Thanks, got it. Proper code looks like:

 function sumW = microstateSum(N)
 n1 = N:-1:0;
 n2 = 0:1:N;
 sumW = sum(factorial(N)./(factorial(n1).*factorial(n2)));