Path: csiph.com!x330-a1.tempe.blueboxinc.net!newsfeed.hal-mli.net!feeder1.hal-mli.net!border3.nntp.dca.giganews.com!Xl.tags.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!local2.nntp.dca.giganews.com!nntp.earthlink.com!news.earthlink.com.POSTED!not-for-mail
NNTP-Posting-Date: Sun, 07 Aug 2011 11:26:51 -0500
Date: Sun, 07 Aug 2011 09:26:54 -0700
From: Patricia Shanahan <pats@acm.org>
User-Agent: Mozilla/5.0 (Windows NT 5.2; WOW64; rv:5.0) Gecko/20110624 Thunderbird/5.0
MIME-Version: 1.0
Newsgroups: comp.lang.java.programmer
Subject: Re: higher precision doubles
References: <j1hqc1$1ch$1@news.albasani.net> <strictfp-20110806003831@ram.dialup.fu-berlin.de> <j1k4db$1n2$1@news.albasani.net> <j1k87t$kol$1@dont-email.me> <j1kb73$h3p$1@news.albasani.net> <j1kg3g$61c$1@dont-email.me> <j1kheh$ta4$1@news.albasani.net> <GMCdnfvkB6IaUaDTnZ2dnUVZ_omdnZ2d@earthlink.com> <j1kj1j$be$1@news.albasani.net> <t8idnWDwz_v8iKPTnZ2dnUVZ_gCdnZ2d@earthlink.com> <j1manb$2lu$1@news.albasani.net>
In-Reply-To: <j1manb$2lu$1@news.albasani.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Message-ID: <nOednS4yGv5WIaPTnZ2dnUVZ_gqdnZ2d@earthlink.com>
Lines: 29
X-Usenet-Provider: http://www.giganews.com
NNTP-Posting-Host: 70.230.203.65
X-Trace: sv3-6iCyDdnjsj8U02LB0rENMo/XYFYc/yEAqlPUNxvQ9MmTxr0hQACeYpNc02UWTm+qIAfQQxwnzTydLBA!tsQCldh4RXjQXCb9/6XryfCsvq5ds6h1I2iJu0lm53LcQ6cBW5MYXQqmNOuBdOz0b2amStNJ9IQE!QQGBCNkt4CTxI/FVesqO13QcpC3ieBvsgR7w4KwyiM/WTw==
X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers
X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly
X-Postfilter: 1.3.40
X-Original-Bytes: 2718
Xref: x330-a1.tempe.blueboxinc.net comp.lang.java.programmer:6854

On 8/7/2011 8:24 AM, Jan Burse wrote:
...
> Lower or higher precisions might be covered by IEEE 754,
> but there are also a couple of other standards around,
> like IEEE 854 which is closer to BigDecimal, since the exponent
> is base 10.

IEEE 754 permits extended forms of the two precisions, 32 bit and 64
bit. Essentially, Java floating point arithmetic is a simplification of
IEEE 754 without e.g. user selection of rounding mode.


>
> I gave Math.sin(2*Math.PI) only as an example of what I
> eventually want to do with the higer precision floats.
> But since I do not have the higher precision floats, I
> showed how the myHighPrecPackage.sin(2*myHighPrecPackage.PI)
> would work with normal precision.

One can often make some particular combination of calculations give a
more precise answer by some variations in the arithmetic. However, this
does not give much indication of the real requirements.

Do calculations involving trig functions of integer multiples of pi need
to be exact in some application, even if trig functions of other angles
have normal rounding behavior? If so, why? Or do you need trig functions
in general to be more precise?

Patricia