[R] problems with integrate ... arguments

[Ravi Varadhan]

Richard,

Your function f() is already vectorized, and it works well (see below).  Therefore, you don't need to create f2().  

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: rvaradhan at jhmi.edu


----- Original Message -----
From: Richard Morey <R.D.Morey at rug.nl>
Date: Thursday, April 9, 2009 8:10 am
Subject: [R] problems with integrate ... arguments
To: r-help at 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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