[Rcpp-devel] Building/linking trouble with cxxfunction()

[Ken.Williams at thomsonreuters.com]

On 2/16/11 3:55 PM, "Douglas Bates" <bates at stat.wisc.edu> wrote:

>I decided that it would be simple enough to write a small package to
>show exactly how you would pass a dgCMatrix to an Rcpp-based C++
>function and create a smat object.


Excellent, thanks!!  I'll grab it and take a look.

>but it is taking a long time.  I don't know if it is a programming
>error or the wrong calling sequence or just a slow algorithm but it
>has been chugging away for 7 minutes.  In constrast, it takes about 2
>seconds to calculate the singular values of that matrix as a dense
>Matrix

That probably indicates a problem - in my experience, using a matrix about
10,000 x 10,000 and about 1% nonzero, the SVD calculation of SVDLIBC is
completely dominated by the time spent reading & writing the data file.
Which is why I wanted to write this wrapper in the first place. =)

--
Ken Williams
Senior Research Scientist
Thomson Reuters
Phone: 651-848-7712
ken.williams at thomsonreuters.com
http://labs.thomsonreuters.com