Bug 14069 - pt not monotonic with large noncentrality
Summary: pt not monotonic with large noncentrality
Alias: None
Product: R
Classification: Unclassified
Component: Accuracy (show other bugs)
Version: old
Hardware: ix86 (32-bit) Windows 32-bit
: P5 normal
Assignee: R-core
Depends on:
Reported: 2009-11-17 10:01 UTC by Jitterbug compatibility account
Modified: 2015-12-14 13:47 UTC (History)
0 users

See Also:


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Description Jitterbug compatibility account 2009-11-17 10:01:24 UTC
From: Jerry.Lewis@biogenidec.com
Full_Name: Jerry W. Lewis
Version: 2.10.0
OS: Windows XP Professional
Submission from: (NULL) (

pt(0,3,200)      # correctly returns 0
pt(-1000,3,200)  # erroniously returns 0.003116595

Since pt(0,df,nc) = pnorm(-nc), there is an easily computed upper bound for
pt(-t,df,nc) where t>0 and nc>0.

Comment 1 Jitterbug compatibility account 2009-11-17 22:47:01 UTC
Audit (from Jitterbug):
Tue Nov 17 16:47:01 2009	ripley	moved from incoming to Accuracy
Comment 2 Brian Ripley 2010-04-11 17:18:37 UTC
changes in 2.12.0