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Message-ID: <alpine.LRH.2.02.1903172219370.6962@key0.esi.com.au>
Date: Sun, 17 Mar 2019 22:41:53 +1100 (AEDT)
From: Damian McGuckin <damianm@....com.au>
To: musl@...ts.openwall.com
Subject: Re: atanhf(x) Slight Accuracy Improvements


Here is the net nesult for the 32-bit version.

To date, the research has only involved FLT_EVAL_METHOD=0.

ATANH(x)  From  .. To      WORST ERROR  % ERROR>EPS/2  MEAN ERROR

Improved:0.00000..0.00012  0.04027*EPS   0.00000%      0.00301*EPS
Original:0.00000..0.00012  0.99741*EPS   0.39818%      0.00581*EPS

Improved:0.00012..0.00100  0.66667*EPS   8.86075%      0.21559*EPS
Original:0.00012..0.00100  0.95814*EPS   7.42942%      0.21211*EPS

Improved:0.00100..0.17157  0.55526*EPS   0.00605%      0.17453*EPS
Original:0.00100..0.17157  1.09363*EPS   8.51956%      0.23306*EPS

Improved:0.17157..0.18248  0.63539*EPS   0.41833%      0.18648*EPS
Original:0.17157..0.18248  1.07990*EPS   5.23646%      0.21706*EPS

Improved:0.18248..0.26667  0.83800*EPS   2.10627%      0.18376*EPS
Original:0.18248..0.26667  1.12385*EPS   8.71681%      0.23764*EPS

Improved:0.26667..0.55000  0.90005*EPS   3.97403%      0.20866*EPS
Original:0.26667..0.55000  1.12779*EPS   9.27245%      0.24201*EPS

Improved:0.55000..1.00000  0.68372*EPS   1.39651%      0.19197*EPS
Original:0.55000..1.00000  0.68372*EPS   1.40897%      0.19207*EPS

Does this sort of gain make it worthwhile pursing a double version?

Regards - Damian

Pacific Engineering Systems International, 277-279 Broadway, Glebe NSW 2037
Ph:+61-2-8571-0847 .. Fx:+61-2-9692-9623 | unsolicited email not wanted here
Views & opinions here are mine and not those of any past or present employer

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