Lambert W Function (hp-42s)

[Werner]

nitpicking: it won't recognize (-1/e,0).
We can add a code slice at the beginning that will turn a complex number with zero imaginary part into a real, as follows:

Code:

@      Re -> Re
@ (Re,0) -> Re
@ (Re,Im) -> (Re,Im)
 REAL?
 0
 CPX?
 COMPLEX
 X#0?
 COMPLEX
 REAL?
 +

or

Code:

 REAL?
 GTO 00
 COMPLEX
 X#0?
 COMPLEX
 REAL?
 +
 LBL 00

Cheers, Werner