Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!mcsun!hp4nl!cwi.nl!jurjen
From: jurjen@cwi.nl (Jurjen NE Bos)
Newsgroups: comp.sys.handhelds
Subject: Re: Accuracy w/ ln and log
Message-ID: <3619@charon.cwi.nl>
Date: 2 Jun 91 13:24:04 GMT
References: <1991May30.120658.3590@panix.uucp>
Sender: news@cwi.nl
Lines: 27

jhawk@panix.uucp (John Hawkinson) writes:

>The following question is really one of accuraccy of the HP48SX, specifically,
>and the answer might not apply to other calculators:
No.  It is not the accuracy of the HP48, but of the number system it uses:
12 decimal digits.

>On the 48sx, you must use either:

>       LOG a                      LN a
>       -----            or:       ----
>       LOG b                      LN b

>        #1                         #2

>So, my question is this: which is more accurate? #1, or #2? (does the
Both are VERY accurate.  The HP48 almost ALWAYS gives the correctly rounded
answer to a logarithm; both LN and LOG.

>48 internally use LOG to compute LN, or vice versa?) Thanx.
Doesn't matter.  The internal logarithms are computed to 15 digits, so there
is no conversion loss you can see.

If the logarithm of a or b happens to fit exactly in 12 digits, one of the two
might be marginally more accurate.
About other calculators: Don't use them.  They do have roundoff in their
logarithms :-)