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Re: number dot (with space)

• To: mathgroup at smc.vnet.net
• Subject: [mg99822] Re: number dot (with space)
• From: Bill Rowe <readnews at sbcglobal.net>
• Date: Fri, 15 May 2009 04:20:49 -0400 (EDT)

On 5/14/09 at 1:40 AM, emin.gahramanov at deakin.edu.au (Emin
Gahramanov) wrote:

>Hi guys, sorry for the silly question (I am a Mathematica dummy). I
>have integrated out an expression, and I do not know how to
>interpret the term like this: (-1. g + r)^4) What throws me off is
>"1. g" (g is a parameter), what is that dot after one
>and there is also a SPACE after the dot and before "g" symbol.
>Sometimes I get smth. like "1. r" what is that supposed to mean? If
>r=2, then how to interpret the latter? Is it 1.2?? Or? Thanks.

The expression "1. g" is the product of 1 and g. Mathematic uses
a space in expressions like this to represent multiplication.
The value 1. will be a machine precision number that isn't quite
1. For example, here is an operation that will generate an
equivalent expression

In[4]:= y = (1. + 1/10^8)*x

Out[4]= 1. x

And I can show the constant isn't quite 1 by doing

In[5]:= y[[1]] - 1

Out[5]= 1.*10^-8