Re: Adding two numbers of high precision results in a number of low precision??

• To: mathgroup at smc.vnet.net
• Subject: [mg56960] Re: Adding two numbers of high precision results in a number of low precision??
• From: Paul Abbott <paul at physics.uwa.edu.au>
• Date: Wed, 11 May 2005 05:24:23 -0400 (EDT)
• Organization: The University of Western Australia
• References: <d5mv2v\$dv0\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```In article <d5mv2v\$dv0\$1 at smc.vnet.net>,
Kees van Schaik <schaik at math.uni-frankfurt.de> wrote:

> how is it possible that if I add two numbers of precision ca. 390 I get
> something of precision 53 back?

It is quite easy. For example, try this

a = 1`390

b = -1`390 + 10^(-335)

Precision[a]

Precision[b]

Precision[a + b]

Cheers,
Paul

--
Paul Abbott                                      Phone: +61 8 6488 2734
School of Physics, M013                            Fax: +61 8 6488 1014
The University of Western Australia         (CRICOS Provider No 00126G)
AUSTRALIA                               http://physics.uwa.edu.au/~paul
http://InternationalMathematicaSymposium.org/IMS2005/

```

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