[R] problem with uniroot

[Ravi Varadhan]

Can you send a minimal, reproducible code so that we can try to help you? 

Ravi.

----------------------------------------------------------------------------
-------

Ravi Varadhan, Ph.D.

Assistant Professor, The Center on Aging and Health

Division of Geriatric Medicine and Gerontology 

Johns Hopkins University

Ph: (410) 502-2619

Fax: (410) 614-9625

Email: rvaradhan at jhmi.edu

Webpage:
http://www.jhsph.edu/agingandhealth/People/Faculty_personal_pages/Varadhan.h
tml

 

----------------------------------------------------------------------------
--------


-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of daniele riggi
Sent: Wednesday, June 03, 2009 11:34 AM
To: r-help at r-project.org
Subject: [R] problem with uniroot

Hi R-users,I'm trying to solve a non linear equation, to find the degrees of
freedom of a mixture of t student. I'm sure i wrote the minimization
equation in the right way, but when i try to run the EM algorithm to
estimate the parameters of the mixture, the following error will appear:

Error in uniroot(function(z) log(z/2) - digamma(z/2) + 1 - log((z + d)/2) +
 :
  f() values at end points not of opposite sign

I don't know how solve this problem, i have already tried using the function
optimize, but it doesn't work.
Someone could help me?
thanks a lot


--
Dr. Daniele Riggi, PhD student
University of Milano-Bicocca
Department of Statistics
Building U7, Via Bicocca degli Arcimboldi, 8
20126 Milano, Italy
cell. +39 328 3380690
mailto: daniele.riggi at gmail.com

	[[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.