[R] R keeps crashing when executing 'rlogspline'

[Charles C. Berry]

On Thu, 31 May 2007, Jacques Wagnor wrote:

> Dear List,
>
> I have a simple model as follows:
>
> x <- rnorm(500)
> library(logspline)
> fit <- logspline(x)
> n <- 1000000
> y <- replicate(n, sum(rlogspline(rpois(1,10), fit))) # last line
>

What you do not see in RGui is this:


  *** caught segfault ***
address (nil), cause 'memory not mapped'

Traceback:
  1: .C("rpqlsd", as.double(c(fit$coef.pol, fit$coef.kts)), 
as.double(fit$knots),     as.double(fit$bound), as.integer(0), qq = 
as.double(p), as.integer(length(fit$knots)),     as.integer(length(p)), 
PACKAGE = "logspline")
  2: qlogspline(pp, fit)
[rest deleted]

I think you are getting zero from rpois(1,10) with larger values of n.

rlogspline does not check for n==0

This results in calling qlogspline( numeric(0), fit ) and generates the 
segfault, I guess.

So figure out what should happen when rpois(1,10) returns zero and avoid 
calling rlogspline in those cases.

If 'zero.value' is a suitable value, then this will work:

> library(logspline)
> x <- rnorm(500)
> fit <- logspline(x)
> res <- sapply(1:50, function(x) sum(rlogspline(x, fit)))
> n <- 1000000
> rp <- rpois(n,10)
> y <- c( zero.value, res )[ rp+1 ] ## table lookup is faster!

Chuck


> The problem I keep getting is Rcrashes when doing the last line.  It
> seems to be fine if n is small, but not if n is 1000000.  The message
> I keep getting is:
>
> "R for Windows GUI front-end has encountered a problem and needs to
> close.  We are sorry for the inconvenience.  If you were in the middle
> of something, the information you were working on might be lost."
>
> Any insights would be appreciated,
>
> Jacques
>
> platform       i386-pc-mingw32
> arch           i386
> os             mingw32
> system         i386, mingw32
> status
> major          2
> minor          5.0
> year           2007
> month          04
> day            23
> svn rev        41293
> language       R
> version.string R version 2.5.0 (2007-04-23)
>
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>

Charles C. Berry                        (858) 534-2098
                                          Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu	         UC San Diego
http://biostat.ucsd.edu/~cberry/         La Jolla, San Diego 92093-0901