MathGroup Archive 2009

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

Search the Archive

Re: Inconsistent behaviour of StudentTDistribution

  • To: mathgroup at smc.vnet.net
  • Subject: [mg103207] Re: [mg103162] Inconsistent behaviour of StudentTDistribution
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Thu, 10 Sep 2009 07:23:17 -0400 (EDT)
  • Reply-to: hanlonr at cox.net

It just needs some help

PDF[StudentTDistribution[f], x]

(f/(f + x^2))^((f + 1)/2)/(Sqrt[f]*Beta[f/2, 1/2])

D[CDF[StudentTDistribution[f], x], x] /. Sign'[x] -> 0 //
 
 FullSimplify[#, {Element[x, Reals], f > 0}] &

(f^(f/2)*(f + x^2)^(-(f/2) - 1/2))/Beta[f/2, 1/2]

% == %% // FullSimplify[#, {Element[x, Reals], f > 0}] &

True


Bob Hanlon

---- Alexey <lehin.p at gmail.com> wrote: 

=============
Hello,
Consider the following:

PDF[StudentTDistribution[f], x]
D[CDF[StudentTDistribution[f], x], x]

The outputs of these expressions must be equal. But in really the
second is useless and confusing.




  • Prev by Date: Re: Print in a loop
  • Next by Date: Re: Mapping to a specific column or row in a matrix
  • Previous by thread: Inconsistent behaviour of StudentTDistribution
  • Next by thread: Re: Inconsistent behaviour of StudentTDistribution