[R] Existence of non-vectorised functions
Ravi Varadhan
rvaradha at jhsph.edu
Tue Nov 26 17:17:45 CET 2002
Dear R-Group:
Recently, I ran into a problem. I was using a function called "I.1",
which evaluates the first-order modified Bessel function of the first
kind, in the package "CircStats". This function is not vectorized,
since it uses a couple of "if" conditions. However, when I called this
function with a vector argument, I got no error/warning messages in
R1.5.1 (under Windows 2000). Furthermore, the results were generally
incorect (please see the attached results). However, if I vectorized
it using "ifelse" everything is fine (I created a function
called "myI.1" to do this). I was wondering if there are functions in
other packages, where such problems exist due to non-vectorization?
thanks,
Ravi.
#######################################################
> require(CircStats)
> I.1(1:10)
[1] 0.5651591 1.5906369 3.9533702 9.7594643 24.3351955
[6] 61.3232698 155.7162813 396.4825232 1005.2747089 2517.6347571
> myI.1(1:10)
[1] 0.5651591 1.5906369 3.9533702 9.7594652 24.3356418
[6] 61.3419369 156.0390965 399.8731348 1030.9147087 2670.9883206
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