Re: [ROOT] Complex Matrix, Complex Vector

From: Valeri Fine (fine@bnl.gov)
Date: Sat May 19 2001 - 01:45:34 MEST


> Thorsten Glebe wrote:
> ... snip ...
> > 
> > All these problems do not exist of course with trivial Vector/Matrix
> > implementations like those of the CLHEP library. Those
> > you can easily incorporate in CINT, but as I mentioned, the performance is
> > (even in compiled code)  low.
> > 
> ... snip...
> 
> I guess it is a matter of my complete ignorance in these issues, but could 
> somebody on the thread elaborate a bit on why C++ implementations of matrix 
> operations are supposed to suffer from low performance? What causes the C++ 
> code doing the matrix inversion to be slow compared to its FORTRAN equivalent?
 
I did not investigate one's packages performance, but from my own experience calling 
virtual functions takes a lot of time. Sometimes  it is much faster to replace it with the plain 
"switch /case" . 
Second:  the "virtual function" does not allow to use "in-line" optimization.

There are other reasons as well.

                                                     Valeri



This archive was generated by hypermail 2b29 : Tue Jan 01 2002 - 17:50:46 MET