From Andreas.Weingessel@ci.tuwien.ac.at  Thu Apr 24 11:24:10 1997
From: Andreas.Weingessel@ci.tuwien.ac.at (Andreas Weingessel)
Date: Thu, 24 Apr 1997 12:24:10 +0200
Subject: R-alpha: Seg. fault in tapply
Message-ID: <199704241024.MAA07829@elendil.ci.tuwien.ac.at>



Calling tapply with a NULL as INDEX argument causes a segmentation
fault on an i-586-linux machine.

So, if for example
	 y<-list(a=3D1:10,b=3D2:5)
then
	tapply(y$a,y$c,mean)
causes a segmentation fault.=20

This seg. fault is produced when a dimension of length integer(0) is
assigned to a list with one element and this object is shown
afterwards. E.g.:

R>  y<-list(a=3D1:10)
R> dim(y) <- integer(length(NULL))
R> y
Segmentation fault

This happens in the code of tapply, when INDEX=3DNULL in the lines

  extent <- integer(length(INDEX))
and
  dim(ans) <- extent


Regards,
	Andreas

************************************************************************
*                          Andreas Weingessel                          *
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R-alpha: Seg. fault in tapply
Andreas Weingessel