# why embedded matlab function failed to determine the size of expression

Asked by yana osman on 18 Jul 2012
Latest activity Commented on by Kaustubha Govind on 6 Aug 2012

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```

"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?

## 1 Comment

Jan Simon on 18 Jul 2012

I have problems to determine the size of u also. Are u and Mean, Std and XNew different variables? Then please edit the question and brush up the formatting.

Does Matlab have a chance to know the size of u?

Is there a reason to overwrite XNew in each iteration of the for j loop?

## Products

Answer by Kaustubha Govind on 18 Jul 2012

Strange. This works fine for me (I'm using R2011b). Perhaps you are using an older version of MATLAB? What about if you pre-allocate Xnew at the top of the function:

```Xnew = zeros(1,3);
```

Kaustubha Govind on 23 Jul 2012

Perhaps there is a run-time error occurring in your code? Is there an error dialog displayed when you continue from the debugger?

It looks like you can set "Data interpolation within time range" on the 'From File' block dialog to "Zero order hold" to turn off linear interpolation.

yana osman on 6 Aug 2012

In my "from file" block does not have :data interpolation within time range" dialog. its only have "file name and "sample time". Any alternative step can i do to turn off linear interpolation? by the way i'm using MATLAB R2009a

Kaustubha Govind on 6 Aug 2012

Yana: Sorry, perhaps the option to turn off interpolation was only introduced in a later release. You could try using Inport blocks to import data - these blocks should have an "Interpolate data" checkbox which you can turn off.

Answer by Fred Smith on 18 Jul 2012

In more recent versions your code should just work. However, in older versions the size of this pattern was not understood:

`    j:j+2`

Simply rewrite it as:

`    j + (0:2)`

HTH,

Fred