From mwelinder at gmail.com  Tue Jul 24 17:18:09 2007
From: mwelinder at gmail.com (mwelinder at gmail.com)
Date: Tue, 24 Jul 2007 17:18:09 +0200 (CEST)
Subject: [Rd] Accuracy of qt for df=1 (PR#9804)
Message-ID: <20070724151809.85C7665981@slim.kubism.ku.dk>

Full_Name: Morten Welinder
Version: 2.2.0
OS: Linux
Submission from: (NULL) (216.223.241.229)


The qt function for df=1 is implemented as...

    q = - tan((P+1) * M_PI_2);

Adding 1 kills accuracy for P near 0.  A better way is to use

   q = cot(P * M_PI_2);
or
   q = 1/tan(P * M_PI_2);



[Rd] Accuracy of qt for df=1 (PR#9804)
mwelinder at gmail.com