Lambert W Function (hp-42s)

[Albert Chan]

(06-11-2020 09:20 AM)Werner Wrote:  

Code:

17 STO+ ST Y @    y'    y'+e^2    a    a

Thanks ! This is more than I expected
Now, we can get W both ways, directly from the stack

1e100
XEQ "eW"   ; eW = 4.44754573894e97
LN         ; W = LN(eW) = 224.843106445
R↓         ; a = 1e100
÷          ; W = a / eW = 224.843106445

Or, to check its accuracy, from definition W eW - a = 0

1e100 XEQ "eW" LN × −     → 0