[R] atlas for R1.1.1 and R1.2 different?

Marcus Eger marcus.eger at physik.uni-marburg.de
Tue Nov 14 13:44:36 CET 2000


Douglas Bates wrote:

> I don't think the presence or absence of atlas should affect the
> results from integrate.  The atlas library is an enhanced, faster
> version of the basic linear algebra subroutines (blas) and a few of
> the lapack subroutines.  Unless the C code in integrate is calling
> these subroutines explicitly, atlas should not affect the results.

An example for the different behaviour is the following:

"prds" <-  function (s,r,sn=1)
1/(pi*sqrt(1-s^2))/(sqrt(2*pi)*sn)*exp(-(r-s)^2/(2*sn^2))


UNDER R1.2:
===========
> integrate(prds, -1,+1,minpts=100,maxpts=NULL,eps=0.01,r=0)
        value        relerr        minpts        lenwrk         ifail
2.735080e-269   7.38275e-08           165            73             0
>


UNDER R.1.1:
============
> integrate(prds, -1,+1,minpts=100,maxpts=NULL,eps=0.01,r=0)
      value      relerr      minpts      lenwrk       ifail
  0.3146147 0.009182386        1023         283           0

.... which makes more sense.
I'm wondering why the same integrate package under R1.1.1 uses atlas,
but under R1.2 it doesn't.

   Marcus


--
+-------------------------------------------------------
| Marcus Eger
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|         marcus.eger at physik.uni-marburg.de (OLD)
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