MathGroup Archive 2009

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Questions about assumptions

  • To: mathgroup at
  • Subject: [mg101804] Re: Questions about assumptions
  • From: Szabolcs <szhorvat at>
  • Date: Fri, 17 Jul 2009 05:06:07 -0400 (EDT)
  • References: <h3n5lq$25m$>

On Jul 16, 3:15 pm, Alexander Erlich <alexander.erl... at>
> 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.

  • Prev by Date: Re: Modify variable names in a loop
  • Next by Date: Integral Fails to Converge
  • Previous by thread: Re: Questions about assumptions
  • Next by thread: Re: Questions about assumptions