What you're looking at isn't meaningful. It's all just rounding error. You're essentially doing this:
I'm guessing there's some phase component that's not defined right yet, but I can't really guess at what you need it to be.
z2 = A*sin(B*(L-x) - w*t);
For the future, please just paste your code using the code formatting tools. I had to retype all that and deal with the sub-pixel ambiguity differentiating the character '1' and 'l'.