On 09/04/2009 10:19 AM, Ravi Varadhan wrote:
Richard,
Your function f() is already vectorized, and it works well (see below). Therefore, you don't need to create f2().
He did say that this was a simplified example.
The problem appears to be in Vectorize, which uses match.call() to get
the args from the call to your f function. match.call() can make
substitutions for ... args, but only seems to do so for one level up,
and the dots are being passed through two levels here: ... as an arg to
integrate, which creates a local function ff, and passes ... through it.
Not sure yet where to fix this...
Duncan Murdoch
f = function(x, const) 2^x + const
testval = 2
integrate(f, 0.5, 1, const=testval)
1.845111 with absolute error < 2.0e-14
Ravi.
____________________________________________________________________
Ravi Varadhan, Ph.D.
Assistant Professor,
Division of Geriatric Medicine and Gerontology
School of Medicine
Johns Hopkins University
Ph. (410) 502-2619
email: rvarad...@jhmi.edu
----- Original Message -----
From: Richard Morey <r.d.mo...@rug.nl>
Date: Thursday, April 9, 2009 8:10 am
Subject: [R] problems with integrate ... arguments
To: r-help@r-project.org
Hi everyone,
I saw this problem dealt with here:
but no one answered that request that I can tell. I'm having the same
problem. I'm having problems passing arguments to functions that I'd
like to integrate. I could swear this worked in the past, but I can't
get it to work now. I'm running R on Windows.
Here's my toy code to reproduce the problem:
R.Version()$version.string
# [1] "R version 2.8.1 (2008-12-22)"
f=function(x,const)
2^x+const
f2=Vectorize(f,c("x"))
testval=2
f2(1:5,testval)
# [1] 4 6 10 18 34
# The vectorized function seems to work right.
integrate(f2,.5,1,c=2)
# Works. Returns
# 1.845111 with absolute error < 2.0e-14
integrate(f=f2,.5,1,const=testval)
# Doesn't work. Returns
# Error in eval(expr, envir, enclos) :
# ..1 used in an incorrect context, no ... to look in
I understand that I don't have to Vectorize this function for it to
work, but the more complicated functions I'm using require Vectorization.
Why can't I pass the argument "const" as a variable, instead of a value?
I don't understand this error.
Thanks in advance,
Richard Morey
--
Richard D. Morey
Assistant Professor
Psychometrics and Statistics
Rijksuniversiteit Groningen / University of Groningen
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