superimpose density line over hist

try

hist(alnlength, prob = TRUE)

moreover I think that you do not need to sample from the Chi-squared 
to draw its density; you could use

dchisq(seq(...), 4))

instead.

I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://www.med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm



----- Original Message ----- 
From: "Albert Vilella" <avilella at gmail.com>
To: <r-help at stat.math.ethz.ch>
Sent: Tuesday, December 13, 2005 2:23 PM
Subject: [R] superimpose density line over hist

Hi all,

I'm trying to superimpose a rchisq density line over a histogram 
with
something like:

hist(alnlength)
lines(density(rchisq(length(alnlength), 4)),col="red")

But the rchisq line won't appear anywhere,

Anyone knows what I am missing here?

Thanks in advance,

   Albert.

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