Re: $Assumptions
- To: mathgroup at smc.vnet.net
- Subject: [mg92629] Re: $Assumptions
- From: Albert Retey <awnl at gmx-topmail.de>
- Date: Thu, 9 Oct 2008 06:34:03 -0400 (EDT)
- References: <gci2ia$ta$1@smc.vnet.net>
Hi,
> I seem to be unable to change some default options globally.
>
> At the top of my notebook I have
>
> $Assumptions = {MaxRecursion -> 30, AccuracyGoal -> 10};
If you want to change default options, use SetOptions. Changing
$Assumptions will not have any effect on NIntegrate, except that you
might introduce unintended side effects. This should do what you want:
SetOptions[NIntegrate,MaxRecursion -> 30, AccuracyGoal -> 10]
you can even check that this has been succesful by evaluating:
Options[NIntegrate]
> Then we I evaluate NIntegrate[Exp[-x^2], {x, 20., 40.}]
> I get 4.78196*10^-176
>
> But if I evaluate NIntegrate[Exp[-x^2], {x, 20., 40.}, MaxRecursion -> 30,
> AccuracyGoal -> 10]
> I get quite a different value, 1.36703*10^-177
>
> I had the same problem trying to change the options for fonts in plots,
> and then I had to add the options I wanted
> in every plot, I mean evaluation something like $TextStyle ={whatever}
> before doing the plots did not work.
Same story here: You need to change the Options of Plot:
SetOptions[Plot, BaseStyle -> {FontSize -> 20}]
>From the documentation:
"As of Version 6.0, $TextStyle has been superseded by BaseStyle and
other options."
There have been complaints about the documentation, but still I think it
is a good idea to first look there if something doesn't work as expected...
hth,
albert