creating a function for my repeating computation

I want to create a function for the following set of repeated computations i will be performing in my work.

d = ((x*b) - y).^2;
test = sum (d(:))/1000;

Your help is much appreciated.

[fafz1203]

please know that the value of x and y is different on every call, it takes different values of x and y every time it's called.

Answer 1

[Walter Roberson]

test = @(b, x, y) sum( reshape( (x*b - y).^2, [], 1) ) / 1000;

Now

result = test(b, x, y);    %a call to the function

Question: do there happen to be exactly 1000 elements in y, so it is computing a mean? If so then

test = @(b, x, y) mean2( (x*b - y).^2 );    %if you have the image processing toolbox

test = @(b, x, y) mean( reshape( (x*b - y).^2, [], 1) );   %if you do not have image processing

For some shapes of x and b and y, it would be possible to use (:) instead of reshape()