How do I limit the repmat?

I am trying to create a function to code or decode a message and was suggested that i use repmat and mod. I understand how the mod works but the repmat is confussing me. lets say my message is:

   MATLAB

and the key is:

 [2,4,6,3]

How would i get the key to become:

 [2,4,6,3,2,4]

to change each of the letters in matlab? I realize that I need to use double to convert the text to numbers and char to convert the changed numbers back to text.

Any help would be Appreciated.

Answer 1

[Sean de Wolski]

One way:

str = 'MATLAB'
key = [2,4,6,3];

%Replicate it to be slightly bigger and lop off the end.
keysz = repmat(key,1,ceil(numel(str)./numel(key)));
keysz = keysz(1:numel(str));

Answer 2

[Azzi Abdelmalek]

x=[2,4,6,3]
y=repmat(x,1,2)  % Duplicate horizontally twice
y=y(1:6)