Get rid of these two useless lines of code:
clear all
clc
They serve no relevant functional purpose, and just cause you bugs (like this one). The only reason beginners put clear at the start of everything that they write is because of this:
Do not put clear at the start of everything. It does not help: it created this bug. It is not related to your code's functionality. Well written code does not need clear (or atleast very rarely): if all variables are preallcoated (as they should be) and code is written in functions (as it should be) then MATLAB's inbuilt memory manager takes quite good care of allocating and clearing variables from memory.
