[This really is a programming question which the posting guide says should have been sent to R-devel, so I have diverted it there.]
dseyv is not an interface to dsyevr, but a separate routine. R does use dsyevr these days, but before R required IEC60559 arithmetic, it also provided the choice of dsyev, as the latter does not require IEC60559. I am not sure what R_exts/Lapack.h is intended to be. If you include $(LAPACK_LIBS) $(BLAS_LIBS) in the building of your package, you will get access to a full double-precision LAPACK library including dsyevr. However, that header file is _not_ part of the R API and is _not_ a list of exports. There is another complication. R imports LAPACK subroutines from either an external LAPACK library or from an LAPACK library it creates. Because some external LAPACK libraries have a broken dsyev(r) but might be in use as a BLAS library, under some circumstances R uses a renamed dsyev(r) as rsyev(r). So it is potentially dangerous to make use of dsyev(r) (and, let me say again, they are not part of the R API). (AFAIR we did this to avoid getting incorrect results on some version of libsunperf.) I suggest you use your own LAPACK routines of known provenance. On Fri, 5 Nov 2004, Jon McAuliffe [EMAIL PROTECTED] wrote: > i want to compute the top k eigenvalues+eigenvectors of a (large) > real symmetric matrix. since it doesn't look like any top-level R > function does this, i'll call LAPACK from a C shlib and then > use .Call. the only LAPACK function i see to do this in > R_ext/Lapack.h is dsyevx. however, i know that in LAPACK dsyevr > can also return a partial eigendecomposition. why is dsyevr not > exported in R_ext/Lapack.h? my superficial understanding is that > dsyevr is "better" (faster? stabler?) for both complete and > partial eigenproblems than dsyevd/dsyevx, but only the complete > eigenproblem interface to dsyevr appears to be exported in > Lapack.h (as dsyev). > > corrections to misunderstandings in the above are welcome. advice > on whether using dsyevr rather than dsyevx is (very) important > for partial decompositions is also gratefully accepted. I am baffled by the problem with your shift key: it does work some of the time but your text is very hard to read when it does not work. -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
