       Re: Converting a number back to a symbol?

• To: mathgroup at smc.vnet.net
• Subject: [mg82900] Re: Converting a number back to a symbol?
• From: Szabolcs Horvát <szhorvat at gmail.com>
• Date: Fri, 2 Nov 2007 05:04:48 -0500 (EST)
• References: <fgenct\$fsd\$1@smc.vnet.net>

```AES wrote:
> If we have an expression containing integer powers of the symbol u0 and
> we know that u0's numerical value is (or at least eventually will be) u0
> = Pi/2, we know what happens if we write
>
>    expr /. {u0 -> Pi/2}
>
> 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?
>

Can you give a full, evaluatable example?

It works for me:

In:= Plus@@(Pi^Range)
Out= Pi + Pi^2 + Pi^3

In:= % /. Pi->2u0
Out= 2 u0 + 4 u0^2 + 8 u0^3

--
Szabolcs

```

• Prev by Date: Re: Re: Re: Setting Negatives to Zero
• Next by Date: Re: Help on drawing intervals
• Previous by thread: Re: Re: Mathematica 6 Graphics Options
• Next by thread: Re: Converting a number back to a symbol?