[R] qt with df<1 (repost)

Enrico Rossi enrico.a.rossi at gmail.com
Sun Oct 12 14:40:07 CEST 2008

Sorry about the html-formatted message. Here it is again in plain text.


The function qt returns NaN for degrees of freedom <1. For example:

> qt(0.5,0.5)
[1] NaN
Warning message:
In qt(p, df, lower.tail, log.p) : NaNs produced

But qt(0.5,0.5) should be 0, since the distribution is symmetric.

> pt(0,0.5)
[1] 0.5

It actually fails with any value, as long as df<1.
Is this a bug, or is there some fundamental reason why this cannot be

Thank you,

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