rectify the error in the code below

number of rows in b = 10;

I want to subtract each row of b with a i get... number of columns in both 'a' and 'b' are 128....

on some evaluation i get a as zero... that time when i execute the below code i get error

 for i = 1 : size(b,1)
    X(i,1) = sum(w * ((a(1,:) - b(i,:)).^2) / (a(1,:) + b(i,:)));
 end

my error is

    ??? Error using ==> mtimes
    Inner matrix dimensions must agree.

    Error in ==> DemoFile at 147
            X(i,1) = sum(w * ((a(1,:) - b(i,:)).^2) / (a(1,:) + b(i,:)));

why am i getting the error... please can someone rectify it... i want the code to work even if the value of a is zero and sort the matrix X....

please can someone rectify it for me...

Answer 1

[Guillaume]

The error is with the multiplication. Is your w scalar?

Answer 2

[Roger Stafford]

If 'w' has more than one column, you will get an error because

   w * ((a(1,:) - b(i,:)).^2)

is performed before the division.

However, I suspect you meant to write

   w .* ((a(1,:) - b(i,:)).^2) ./ (a(1,:) + b(i,:))

if 'w' is a row vector with 128 columns or

   w * ((a(1,:) - b(i,:)).^2) ./ (a(1,:) + b(i,:))

if it is a scalar.

[Guillaume]

I thought at first that the division was meant to be element-wise as well. But the result is assigned to a scalar ( X(i, 1)), so it has to be a matrix division.