Re: confused about asserting variable is element of
- To: mathgroup at smc.vnet.net
- Subject: [mg103124] Re: [mg103084] confused about asserting variable is element of
- From: Patrick Scheibe <pscheibe at trm.uni-leipzig.de>
- Date: Tue, 8 Sep 2009 06:01:10 -0400 (EDT)
- References: <200909070636.CAA04019@smc.vnet.net>
Hi,
you have to state that Mathematica should use your assumption
Assuming[a \[Element] Reals, Simplify[Im[a]]]
Maybe you should have a look at the help of the global variable
$Assumptions
Cheers
Patrick
On Mon, 2009-09-07 at 02:36 -0400, dushan wrote:
> I'm still learning Mathematica (using 7.0.1) and don't understand
> Mathematica's response. After finally finding out how to assert that a
> variable is real, I tried to verify this by asking Mathematica to show me that
> it knew the imaginary part of the variable is zero. But I couldn't
> find a way to do that.. Here're my instructions:
>
> In[1]:= a (ESC)el(ESC) Reals
> Out[1]:= a (the element-of symbol) Reals
>
> In[2]:= ##Im[a]
> Out[2]:= Im[a]
>
> where '##' is any of {null, Refine[, Simplify[, FullSimplify[}. I
> also tried some other combinations, such as 'a^2 - Re[a]^2', but these
> didn't help either.
>
> What am I doing wrong? How do I verify such things?
>
> Thanks.
>
> - Dushan Mitrovich
>
- References:
- confused about asserting variable is element of Reals
- From: dushan <dushanm@spinn.net>
- confused about asserting variable is element of Reals