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MathGroup Archive 1992

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Re: Integrating Normal Distributions gives the wrong answer

  • To: mathgroup at yoda.physics.unc.edu
  • Subject: Re: Integrating Normal Distributions gives the wrong answer
  • From: tlm at tantalus.scl.ameslab.gov (Tom Marchioro)
  • Date: Mon, 14 Sep 92 13:19:06 CDT

[]
[]I was intending to as y'all about the suitability of running Mma 2.1 on a  
[]Mac Powerbook 170 since I was working at home over the weekend trying to  
[]figure out convergence rates of covariance matrices; alas, now that I'm  
[]playing with Mma 2.0 on my office NeXTstation, I'm wondering whether I  
[]should spring for Maple and avoid the "beautifully formatted, incorrect  
[]answers" syndrome which my colleague is chortling about at the moment.
[]
[]The issue is integrating normal distribution functions. Given that I define  
[]the Gaussian density function,
[]
[]Anyhow, is this misbehavior of Mathematica fixed in v2.1 or is there some  
[]sort of a rationale for such behavior? It seems like I'm trying such a  
[]simple exercise that there isn't much room for operator error....
[]
No, hard to make an error on something like this!!  Anyway, (1)  this is 
fixed in 2.1 (it was an error in the hypergeometric rule) and (2) I
can even give you a fix now if you don't want to spring for 2.1.  That
is, I helped the guys at WRI figure out how loading the new symbolic 
integration package would interact with the old Mma (i.e. 2.0.4.5)
version.  Thus, I have the entire *new andimproved* symbolic integration
package, which WRI said I was free to distribute.  I can NeXTmail it to
you if you'd like.

I would still recommend you getting 2.1 (I'm going to) becuase there
are lots of other fixes, in particular the contour plots and the eigenvalue
routines are much improved (I'm told), but if this is all you care about
and you don't have the $50. . . . 

Incidentally, I'm a theoretical physicist specializing in coherent states
(i.e. Gaussian wavepackets) so you can imagine how infuriating the old 
integration package was for me.  

Tom







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