Re: Converting a number back to a symbol?
- To: mathgroup at smc.vnet.net
- Subject: [mg82904] Re: Converting a number back to a symbol?
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Sat, 3 Nov 2007 03:20:22 -0500 (EST)
- Organization: The Open University, Milton Keynes, UK
- References: <fgenct$fsd$1@smc.vnet.net>
AES wrote:
<snip>
> But what about the reverse case: we have an expression containing
> various integer powers of Pi, and we want to replace all the explicitly
> appearing Pi's by 2 u0. Writing
>
> expr /. {Pi-> 2 u0}
>
> doesn't seem to do it.
>
> Is there a way?
Please, could you give a concrete example where such a transformation
does not work?
In[1]:= expr = Pi + Pi^2 + Pi^3 + (Pi/2 + (Pi/2)^2 + (Pi/5)^3) + 1/(Pi +
Pi^2 + Pi^3)
Out[1]= 2 3
3 Pi 5 Pi 126 Pi 1
---- + ----- + ------- + --------------
2 4 125 2 3
Pi + Pi + Pi
In[2]:= expr /. Pi -> 2 u0
Out[2]= 3
2 1008 u0 1
3 u0 + 5 u0 + -------- + --------------------
125 2 3
2 u0 + 4 u0 + 8 u0
Regards,
--
Jean-Marc