Re: Converting a number back to a symbol?
- To: mathgroup at smc.vnet.net
- Subject: [mg82966] Re: Converting a number back to a symbol?
- From: AES <siegman at stanford.edu>
- Date: Mon, 5 Nov 2007 05:01:33 -0500 (EST)
- Organization: Stanford University
- References: <fgenct$fsd$1@smc.vnet.net>
In article <fgenct$fsd$1 at smc.vnet.net>, AES <siegman at stanford.edu>
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 . . .
My abject apologies for this -- utter stupidity in action.
My test case was (in separate cells):
u0 = Pi/2;
f = u0 + 2 u0^2 + 4 u0^2
f /. {Pi -> 2 u0}