       Re: Is there a simple way to transform 1.1 to 11/10?

• To: mathgroup at smc.vnet.net
• Subject: [mg92979] Re: Is there a simple way to transform 1.1 to 11/10?
• From: dh <dh at metrohm.ch>
• Date: Wed, 22 Oct 2008 05:36:18 -0400 (EDT)
• References: <gdkajv\$4r2\$1@smc.vnet.net>

```

Hi Alain,

Rationalize[x,0] does not give a rational approx. without errors as the

"0" may imply. Instead it gives an approximation with the precision of

x. Even Rationalize[x,dx] does at most give an approximation with a

precision of x (even if dx is smaller).

hope this helps, Daniel

Alain Cochard wrote:

> The obvious

>

>     In:= x=1.1`Infinity

>

> is not syntactically correct.

>

> I understand that SetPrecision[1.1,Infinity] does not work either:

>

>     In:= SetPrecision[1.1,Infinity]

>

>             2476979795053773

>     Out= ----------------

>             2251799813685248

>

>     In:= N[%,20]

>

>     Out= 1.1000000000000000888

>

> I searched the newsgroup and thought I had the solution with Rationalize:

>

>     In:= Rationalize[1.1,0]

>

>             11

>     Out= --

>             10

>

> But

>

>     In:= Rationalize[1.000000001,0]

>

>             999999918

>     Out= ---------

>             999999917

>

>     In:= N[%,20]

>

>     Out= 1.0000000010000000830

>

> So any simple way?

>

> Thanks,

> Alain

>

--

Daniel Huber

Metrohm Ltd.

Oberdorfstr. 68

CH-9100 Herisau

Tel. +41 71 353 8585, Fax +41 71 353 8907

E-Mail:<mailto:dh at metrohm.com>

Internet:<http://www.metrohm.com>

```

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