[Rd] Accuracy of qt for df=1 (PR#9804)

maechler at stat.math.ethz.ch maechler at stat.math.ethz.ch
Wed Jul 25 09:57:26 CEST 2007

>>>>> "MW" == Morten Welinder <mwelinder at gmail.com>
>>>>>     on Tue, 24 Jul 2007 17:18:09 +0200 (CEST) writes:

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

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

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

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

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

Yes, indeed, thanks a lot, Morten!!

     ((BTW: you should really upgrade your version of R))

Best regards,

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