Solve App and ABS() and IP()

[cclinus]

Hello,

I have two equations.
E1: S=(IP(X/L)*IP(Y/M)+IP(X/M)*IP(Y/L)+ABS(IP(X/L)*IP(Y/M)-IP(X/M)*IP(Y/L)))*0.5

E2:C=IP(X/L)*IP(Y/(2*M-2) )+IP(X/(2*M-2))*IP(Y/L)+ABS(IP(X/L)*IP(Y/(2*M-2))-IP(X/(2*M-2))*IP(Y/L))

When I solve them one by one, the answer is correct:
   
   

But, if I solve them at the same time, the answer of E2 is not correct.
   

Is it a bug?

  Solve1.hpappdir.zip (Size: 833 bytes / Downloads: 4)
21-10-2015 attachment updated

Updated on 22-10-2015
I modify the equations to as follows. They have the same problem.
E1:C=IP(X/(2*M-2))*IP(Y/L)*2
E2:B=A

If solve E1 and E2 at the same time, the answer or E1 is not correct.