Services & ResourcesWolfram ForumsMathGroup Archive

[Date Index] [Thread Index] [Author Index]

Re: This should evaluate to zero

• To: mathgroup at smc.vnet.net
• Subject: [mg39956] Re: [mg39926] This should evaluate to zero
• From: "Y.A.Tesiram" <yas at pcomm.hfi.unimelb.edu.au>
• Date: Thu, 13 Mar 2003 03:02:09 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

Hi,
As you have written it, your expression is exact. Forcing a numerical
approximation of the expression with

N[ArcSinh[1]-Log[3363+2378*Sqrt[2]]/10]

gives

0.

-- a very very small number which for all purpose and sense is zero.
Rather than use integers in your expression you can use reals by writing
the decimal point. Mathematica will retrun a very very small number
depending on the setting of the variable $MaxExtraPrecision and the very
small number can be carried through in subsequent calculations. Some
degree of care must be taken in deciding what level of numerical precision
is needed and the actual problem at hand.

Yas


On Wed, 12 Mar 2003, jf alcover wrote:

> Bonjour,
> Methinks that the following expression should evaluate to zero,
> but it does not, even with
FullSimplify :
>     ArcSinh[1]-Log[3363+2378*Sqrt[2]]/10
> Could anyone explain ?
>
>

• Follow-Ups:
  • Re: Re: This should evaluate to zero
    • From: Dr Bob <drbob@bigfoot.com>