Re: $Assumptions

*To*: mathgroup at smc.vnet.net*Subject*: [mg92639] Re: $Assumptions*From*: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>*Date*: Thu, 9 Oct 2008 06:35:57 -0400 (EDT)*Organization*: The Open University, Milton Keynes, UK*References*: <gci2ia$ta$1@smc.vnet.net>

Ruth Lazkoz SÃ¡ez wrote: > I seem to be unable to change some default options globally. > > At the top of my notebook I have > > $Assumptions = {MaxRecursion -> 30, AccuracyGoal -> 10}; > > 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. What you want is *SetOptions* (Note that $Assumptions has nothing to do with options but with assumptions such as x > 0 or Element[n, Integers]) In[166]:= SetOptions[NIntegrate, {MaxRecursion -> 30, AccuracyGoal -> 10}]; NIntegrate[Exp[-x^2], {x, 20., 40.}] Out[167]= 1.36703*10^-177 Regards, -- Jean-Marc