Re: Questions about assumptions
- To: mathgroup at smc.vnet.net
- Subject: [mg101804] Re: Questions about assumptions
- From: Szabolcs <szhorvat at gmail.com>
- Date: Fri, 17 Jul 2009 05:06:07 -0400 (EDT)
- References: <h3n5lq$25m$1@smc.vnet.net>
On Jul 16, 3:15 pm, Alexander Erlich <alexander.erl... at gmail.com> wrote: > Hello, > > I would like to make assumptions like e.g. Element[a,Reals] or b>0 or > simlar ones global in order to avoid using Refine with long assumption > lists every tome. For this purpose, I've found $Assumptions. But I > encountered the following problem: > > In[5]:= $Assumptions = Element[g, Reals] > > Out[5]= g \[Element] Reals > > In[6]:= Conjugate[g] > > Out[6]= Conjugate[g] > > Why didn't Mathematica just return g? > > Maybe, there is a different, or even better way to make assumptions > global to the whole notebook, so that they are considered > automatically (and without Refine or similar)? > Using $Assumptions does not spare having to type Simplify/Refine. It's only to avoid typing the assumptions each time. It *is* possible to ask Mathematica to apply Refine to each output (see $Post), but be careful with this: Refine/Simplify cannot be applied to anything, or they can be very slow with some expressions.