Accuracy of Free42 and DM42
12-22-2017, 07:17 PM (This post was last modified: 12-22-2017 07:19 PM by Dieter.)
Post: #21
 Dieter Senior Member Posts: 2,397 Joined: Dec 2013
RE: Accuracy of Free42 and DM42
(12-21-2017 08:30 AM)Thomas Okken Wrote:  Found it -- the special case for 45° is coded like

if (x == 45) result = sqrt(0.5)

May I ask why this is required? The sine for 45° ±1 ULP seems to be fine, so why has the 45° case to be handled separately?

Here and there it looks like my Free42 version 1.5.5 has the last (34th) digit sometimes truncated instead of rounded, but this is fine by me. On the other hand I seem to remember a remark - maybe by yourself - saying that some of the routines in the Decimal version may not return 34 exact digits since they originally had been used in the binary version with less precision (maybe 25 digits?). Since we're now at version 2.0x: can you say something about the accuracy level of Free42 in general? Does it - usually - provide full 34-digit accuracy?

Here I remember the HP15C Advanced Functions Handbook including a detailled documentation of the various error levels. Which shows that even a calculator with proven reliability will not always get all its returned digits right. Think 3201. ;-)

Dieter
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 Messages In This Thread Accuracy of Free42 and DM42 - Dieter - 12-20-2017, 08:16 PM RE: Accuracy of Free42 and DM42 - Massimo Gnerucci - 12-20-2017, 08:24 PM RE: Accuracy of Free42 and DM42 - Thomas Okken - 12-20-2017, 08:26 PM RE: Accuracy of Free42 and DM42 - Dieter - 12-20-2017, 08:36 PM RE: Accuracy of Free42 and DM42 - Thomas Okken - 12-20-2017, 08:44 PM RE: Accuracy of Free42 and DM42 - grsbanks - 12-20-2017, 08:27 PM RE: Accuracy of Free42 and DM42 - Thomas_Sch - 12-21-2017, 05:54 PM RE: Accuracy of Free42 and DM42 - Thomas Okken - 12-21-2017, 05:58 PM RE: Accuracy of Free42 and DM42 - Thomas_Sch - 12-21-2017, 06:39 PM RE: Accuracy of Free42 and DM42 - salvomic - 12-21-2017, 07:19 PM RE: Accuracy of Free42 and DM42 - Thomas Okken - 12-21-2017, 07:53 PM RE: Accuracy of Free42 and DM42 - salvomic - 12-21-2017, 09:01 PM RE: Accuracy of Free42 and DM42 - Thomas Okken - 12-21-2017, 03:17 AM RE: Accuracy of Free42 and DM42 - Dieter - 12-21-2017, 07:56 AM RE: Accuracy of Free42 and DM42 - J-F Garnier - 12-21-2017, 07:52 AM RE: Accuracy of Free42 and DM42 - Thomas Okken - 12-21-2017, 08:30 AM RE: Accuracy of Free42 and DM42 - toml_12953 - 12-21-2017, 08:45 AM RE: Accuracy of Free42 and DM42 - Thomas Okken - 12-21-2017, 08:57 AM RE: Accuracy of Free42 and DM42 - Dieter - 12-22-2017 07:17 PM RE: Accuracy of Free42 and DM42 - grsbanks - 12-21-2017, 08:53 AM RE: Accuracy of Free42 and DM42 - Thomas Okken - 12-21-2017, 05:52 PM RE: Accuracy of Free42 and DM42 - Thomas Okken - 12-22-2017, 08:43 PM RE: Accuracy of Free42 and DM42 - Werner - 12-22-2017, 09:11 PM

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