Thanks a lot mister_e,

I added your suggestion, which will probably help in the long run. However, I still get the same result for Cos(x) = 71 no matter what I give as x. When edited out of some of the lines that had "global" in them, as suggested in an earlier post, was I supposed to replace "global" with something else? Here are some of the lines I deleted from various places in the program:

GLOBAL X_L, X_H, Y_L, Y_H, Z_L, Z_H, SHIFT
GLOBAL ATAN
GLOBAL SINCOS
GLOBAL Shifter

I don't really understand what these lines did in the original assembly code.
I also wonder if I defined any of the variables wrong. RV, Dir, _C, and _Z are defined inside the assembly code, and the other variables are named in the pbp code. Strange that the ATAN functions great, just the SINCOS having difficulties.