HP Prime crashes in Function and Graph 3D App.

[Albert Chan]

Hi lyuka

HP Prime emulator had bugs.
I downloaded Emu, Build 2.1.14181 (2018 10 16), for Win 7
After some usage, I was unable to purge variable y, even after a restart

CAS> restart
CAS> [y, z] := [1, 2]
CAS> purge(y,z)     → "No such variable y", 2
CAS> [y, z]            → [1, z]

To "fix" it, I had to do a hard reset (via. menu Calculator, Reset)

Code:

//LW0 - Principal branch of the Lambert W function
    ...
    r := abs(y - p); // correction radius;
  UNTIL 0 == r OR q <= r; // convergence check
  return p;
END;

Off topics: Why did you change convergence check ?
q <= r should be (q < 1 and q <= r), to avoid false positives.