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(28/48/50) Lambert W Function
03-23-2023, 12:16 AM (This post was last modified: 03-23-2023 12:17 AM by Albert Chan.)
Post: #8
RE: (28/48/50) Lambert W Function
(03-22-2023 07:30 PM)John Keith Wrote:  y = sqrt(1+e*x)
...
With 'a' determined empirically to be 2.036, final formula is:

-1 + 2.036*ln((1 + 1.14956131*y)/(1 + 0.4549574*ln(1 + y))

Recurrence from same paper, also from "Guaranteed- and high-precision
evaluation of the Lambert W function" by Lajos Lóczi.

B'(x) = (B(x)/(1 + B(x))*(1 + ln(x/B(x))

There is a flaw with Iacono and Boyd W guess formula.
If x is tiny enough, below 6e-10, it could return a negative guess.
This cause Newton formula to take a log of negative number, which crash it.
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Messages In This Thread
(28/48/50) Lambert W Function - John Keith - 03-20-2023, 08:43 PM
RE: (28/48/50) Lambert W Function - Albert Chan - 03-23-2023 12:16 AM
RE: (28/48/50) Lambert W Function - Gil - 01-29-2024, 11:04 AM
RE: (28/48/50) Lambert W Function - Gil - 01-29-2024, 02:47 PM
RE: (28/48/50) Lambert W Function - Gil - 01-29-2024, 06:46 PM
RE: (28/48/50) Lambert W Function - Gil - 01-29-2024, 09:50 PM
RE: (28/48/50) Lambert W Function - Gil - 01-30-2024, 12:33 AM
RE: (28/48/50) Lambert W Function - Gil - 01-30-2024, 12:04 PM
RE: (28/48/50) Lambert W Function - Gil - 01-30-2024, 02:52 PM
RE: (28/48/50) Lambert W Function - Gil - 01-31-2024, 07:10 PM



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