Input.T_11 is defined in Main.m. Main.m calls Func_Task_11.m but does not pass Input to Func_Task_11() so when you get inside Func_Task_11, the Input variable is not in scope. Remember each function has it's own workspace separate from the others. If you want input in Func_Task_11(), you need to pass it in
as the first line.
Also, do not use eps as a variable name - it's a built-in function.