The problem is that you are using variables that don't exist. Specifically, the names are close to what they should be, but they aren't exactly right.
In this case, the compiler isn't being very helpful at all. Instead of saying that they don't exist, the compiler is choking on them. It seems that the error only occurs when the invalid names are used in the abs() calls. At least the compiler is telling you which line(s) fail.
It also looks like you've discovered a compiler bug. I'll leave it to you to report it, instructions are in the compiler output. Have fun!
I'll also leave it to you to track down each specific problem in your code. It shouldn't be too difficult, now that you know what the general issue is.
If this answers your question, please click on the check mark to accept. Let's keep up on forum maintenance. ;-)