December 2019 - Challenge

<< November January >>


Approximating absolute value.
Find an expression with no more than 15 operations (+, -, *, /) that approximates the absolute value function on the interval [-1,1] with an MSE (mean squared error) of no more than 0.0001.

For example, (x+1)/2 can be computed with only two operations and has an MSE of 1/6.



Bonus '*' for the best approximation (currently 1.803E-7).




We will post the names of those who submit a correct, original solution! If you don't want your name posted then please include such a statement in your submission!

We invite visitors to our website to submit an elegant solution. Send your submission to the ponder@il.ibm.com.

If you have any problems you think we might enjoy, please send them in. All replies should be sent to: ponder@il.ibm.com

Challenge: 3/12/2019 @ 12:00 PM EST
Solution: 03/01/2020 @ 12:00 PM EST
List Updated: 26/01/2020 @ 12:00 PM EST

People who answered correctly:

*Oleg Vlasii (04/12/2019 02:56 PM IDT)
James Dow Allen (04/12/2019 06:22 PM IDT)
Guillermo Wildschut (04/12/2019 10:27 PM IDT)
Albert Stadler (04/12/2019 11:01 PM IDT)
Walter Sebastian Gisler(05/12/2019 04:30 PM IDT)
Deane Stewart (05/12/2019 07:52 PM IDT)
Benjamin Buhrow (05/12/2019 08:01 PM IDT)
*Arthur Vause (05/12/2019 04:01 PM IDT)
Daniel Hammack (06/12/2019 01:05 AM IDT)
Muralidhar Seshadri (06/12/2019 02:03 AM IDT)
Sanandan Swaminathan (06/12/2019 05:28 AM IDT)
Michael J. Swart (06/12/2019 04:27 PM IDT)
Kurt Foster (06/12/2019 06:38 PM IDT)
Hugo Pfoertner (07/12/2019 03:18 AM IDT)
Lorenz Reichel (07/12/2019 10:09AM IDT)
Janne Junnila (07/12/2019 06:36 PM IDT)
Deron Stewart (07/12/2019 06:58 PM IDT)
Matthias Baur (08/12/2019 03:03 AM IDT)
Eden Saig (08/12/2019 11:48 PM IDT)
Michael Liepelt (09/12/2019 04:28 PM IDT)
Hannes Planatscher (09/12/2019 06:47 PM IDT)
*Alper Halbutogullari (09/12/2019 11:13 PM IDT)
Fletcher Dostie (10/12/2019 01:48 AM IDT)
*Bertram Felgenhauer (10/12/2019 08:14 AM IDT)
John Reid (10/12/2019 11:57 AM IDT)
Lorenzo Gianferrari Pini (10/12/2019 02:30 PM IDT)
Peter Huggins (11/12/2019 07:48 PM IDT)
Thomas Huet (11/12/2019 08:19 PM IDT)
*Florian Fischer (12/12/2019 12:55 AM IDT)
*Andreas Stiller (12/12/2019 02:27 AM IDT)
Marco Bellocchi (13/12/2019 02:46 AM IDT)
Maksym Voznyy (13/12/2019 05:17 AM IDT)
Vladimir Volevich (13/12/2019 02:34 PM IDT)
Latchezar Christov (13/12/2019 04:13 PM IDT)
Stefan Wirth (13/12/2019 07:43 PM IDT)
Yusuf Attarbashi (14/12/2019 12:34 AM IDT)
Harald Bögeholz (14/12/2019 05:43 AM IDT)
Jacoby Jaeger (14/12/2019 06:29 AM IDT)
Richard Gosiorovsky (14/12/2019 06:06 PM IDT)
Andreas Knüpfer (14/12/2019 08:43 PM IDT)
David Greer (15/12/2019 01:03 PM IDT)
Aviv Nisgav (15/12/2019 10:13 PM IDT)
*Bert Dobbelaere (16/12/2019 01:12 AM IDT)
Yasodhar Patnaik (16/12/2019 05:45 AM IDT)
Rob Pratt (16/12/2019 05:56 AM IDT)
Soumitra Agarwal (17/12/2019 02:58 AM IDT)
Sebastian Bohm & Martí Bosch (17/12/2019 01:34 PM IDT)
David Smalling (18/12/2019 12:39 AM IDT)
Victor Chang (19/12/2019 11:15 PM IDT)
Todd Will (20/12/2019 06:40 PM IDT)
Kang Jin Cho (20/12/2019 08:42 PM IDT)
Daniel Bitin (21/12/2019 04:55 PM IDT)
Dipto Thakurta (22/12/2019 08:28 AM IDT)
Amos Guler (22/12/2019 12:26 PM IDT)
Tyler Mullen (23/12/2019 02:34 AM IDT)
Daniel Chong Jyh Tar (24/12/2019 10:13 AM IDT)
Charles Joscelyne (24/12/2019 06:50 PM IDT)
Fabio Michele Negroni (24/12/2019 07:21 PM IDT)
Franciraldo Cavalcante (25/12/2019 01:22 AM IDT)
Dieter Beckerle (25/12/2019 09:12 PM IDT)
Kipp Johnson (25/12/2019 10:34 PM IDT)
Hermann Jurksch (28/12/2019 07:57 PM IDT)
JJ Rabeyrin (29/12/2019 12:55 AM IDT)
Motty Porat (29/12/2019 02:23 AM IDT)
Michael Schuresko (29/12/2019 02:41 AM IDT)
Shouky Dan & Tamir Ganor (29/12/2019 08:33 AM IDT)
Erik Wuenstel (31/12/2019 01:32 AM IDT)
Aaron Freedman (31/12/2019 02:35 AM IDT)
Stephen Barr (31/12/2019 08:06 AM IDT)
*Calvin Pozderac (31/12/2019 07:51 PM IDT)
Radu-Alexandru Todor (01/01/2020 02:13 AM IDT)
Li Li (01/01/2020 07:54AM IDT)
*Oscar Volpatti (01/01/2020 12:37 PM IDT)
Gert Schlenker (03/01/2020 11:55 AM IDT)
David Keyes (03/01/2020 11:08 PM IDT)
Toprak Göke (06/01/2020 11:55 PM IDT)
Rogerio Ponce da Silva (10/01/2020 08:15 PM IDT)
David Keyes (13/01/2020 06:00 PM IDT)
Inigo Quilez (17/01/2020 11:05 PM IDT)
Christopher Dyken (22/01/2020 07:31 PM IDT)
Reda Kebbaj (24/01/2020 11:46 PM IDT)