Unidentified function or variable in Matlab cannot figure out

I'm trying to write a for loop with a counter. The counter starts at 1 and goes up to 5000. I want the function to use all the numbers up to 5000. This is what I have so far.

 j = 1;
 for i = 1:length(RT)
    if RT(i) < 5000 ;
        newRT(j) = RT(i);
        j = j+1;
    end
end

Is there something wrong with my code? Matlab will not display anything. It is saying the variable RT is undefined.

[per isakson]

Nothing in your code indicates that RT is defined!

[Josh]

if RT were defined as an array of data, would the code work?

As in RT is an array of data and all i want is the data whose values are less than 5000.

[Josh]

Thank you!

Answer 1

[per isakson]

Yes, I cannot see any problem. This code

    RT = 1e4 * rand( 1, 100 ); 
    jj = 1;
    for ii = 1:length(RT)
        if RT(ii) < 5000 ;
            newRT(jj) = RT(ii);
            jj = jj+1;
        end
    end
    whos newRT

produce this output

     Name       Size            Bytes  Class     Attributes
     newRT      1x56              448  double