Code is wrong?

[huazhusun]

Hey, I found something weird s the codes.
You set
LMxr = (alpha * LMx + beta * LMy + (1 - alpha) * LMx[2] / 2 - beta * LMy[2] / 2)
LMyr = (-beta * LMx + alpha * LMy + beta * LMx[2] / 2 + (1 - alpha) * LMy[2] / 2)

however, (1 - alpha) * LMx[2] / 2 - beta * LMy[2] / 2) and beta * LMx[2] / 2 + (1 - alpha) * LMy[2] / 2)
will be cleared in
dXnose = (LMxr[1] - LMxr[2] + LMxr[4] - LMxr[2]) / 2
dYnose = (LMyr[3] - LMyr[2] + LMyr[4] - LMyr[2]) / 2
.The result is totally same as
LMxr = (alpha * LMx + beta * LMy
LMyr = (-beta * LMx + alpha * LMy

so I think maybe threre may be some wrong when implement the code.