why embedded matlab function failed to determine the size of expression

Hi all,

u is an input from the output of continous state.so, for each time (1 x 3) matrix will come out, so

      u matrix = 1 x 3

      Mean = 1 x 450

is a mean of samples.This input from workspace which consist 150 times with 3 variables so its matrix is (1 x 450). but we only need (1 x 3) matrix to evaluate for each time

      Std = 1 x 450

is a standard deviation of samples.Same description as above(mean)

      Xnew = 1x3

is an outpyt from the equation Xnew = u-mean/std

Example;

for time 1

Xnew = u-Mean(1,1:3)

time 2

Xnew = u-Mean(1,4:6);

untill time 150

i'm trying to do loop in embedded matrix function as below command:

   function Xnew = stats(u,Mean, Std)
   %#eml

   for j=1:150,
   Xnew = (u-Mean(1,j:j+2))./Std(1,j:j+2);
   end

unfortunately i received this error,

"Could not determine the size of this expression"

I'm doing looping because i want to pick the submatrix that will be used in the equation.

What should i change above command so as i can get the result as i want? anybody have idea?