Have you tried learning to use the debugger to step through you code line by line?
If you would use the smart indentation, you would notice that you've put the cd inside your loop. Luckily it does nothing, as you didn't change the current directory (nor should you: readtable allows you to specify a full or relative path).
The line with Irr_=[Irr]; looks like you want to store something over several iterations of your loop. However, you aren't changing the variable at all here.
