R help - Mar 2011 - pmt

I am working with the pmt function in the {mnormt} package, and i am getting
negative values returned.  the following is an example of one of my outputs:

pmt(x = c(3.024960, -1.010898), mean = c(21.18844, 21.18844), S
matrix(c(.319,.139,.139,0.319), 2, 2),df = 42)
# -6.585641e-18

Any help on why i'm getting negative numbers would be very much appreciated.

THanks!

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That is essentially zero, because you are so far out in the left tail of the
distribution.  So, you can ignore the negative sign and treat it as zero.

Ravi.
____________________________________________________________________

Ravi Varadhan, Ph.D.
Assistant Professor,
Division of Geriatric Medicine and Gerontology
School of Medicine
Johns Hopkins University

Ph. (410) 502-2619
email: rvaradhan at jhmi.edu


----- Original Message -----
From: statfan <irene_vrbik at hotmail.com>
Date: Sunday, March 27, 2011 1:06 pm
Subject: [R] pmt
To: r-help at r-project.org

> I am working with the pmt function in the {mnormt} package, and i am
getting
>  negative values returned.  the following is an example of one of my
outputs:
>  
>  pmt(x = c(3.024960, -1.010898), mean = c(21.18844, 21.18844), S > 
matrix(c(.319,.139,.139,0.319), 2, 2),df = 42)
>  # -6.585641e-18
>  
>  Any help on why i'm getting negative numbers would be very much
appreciated.
>  
>  THanks!
>  
>  --
>  View this message in context: 
>  Sent from the R help mailing list archive at Nabble.com.
>  
>  ______________________________________________
>  R-help at r-project.org mailing list
>  
>  PLEASE do read the posting guide 
>  and provide commented, minimal, self-contained, reproducible code.