question about fun defining

I want to create this fun as below:

R=rand(100);
diff=rand(25);
sum_r1=rand(25);;

fun =@(x) x(:)+x(:).*diff(:)./sum_r1(:);
R_im=nlfilter(R,[2 2],fun);

In fact, I want to add the amount of (diff/sum_r1).x(:) in each neighborhood of 2 by 2 to x(:); I mean I have 1 diff and 1 sum_r1 for every 2 by 2 neighborhood of R. But it gives me an error!

Can anybody please help me?

[Walter Roberson]

What error does it give?

Note: it is not a good idea to use a variable named "diff" as that will interfere with use of the MATLAB function named "diff"

[Andrea]

??? Error using ==> times Matrix dimensions must agree.

Error in ==> @(x)x(:)+x(:).*diff(:)./sum_r1(:)

[Walter Roberson]

In your code, you do not have 1 diff and 1 sum_r1 for each 2 x 2 neighborhood in R: in your code, you have 1 diff and 1 sum_r1 total

Also, watch out: there are 2500 non-overlapping 2 x 2 neighborhoods in a 100 x 100 matrix, not merely 25. And nlfilter() does sliding windows, not non-overlapping windows.

Perhaps you should consider using blkproc() instead of nlfilter()

[Andrea]

Thanks. I will give it a try.