🚀 go-pugleaf

In article <45ld1i$m7i@cicg-communication.grenet.fr>, enseeg14@grenet.fr () writes:
[..]
> C has always been the language where _THE PROGRAMMER_ could make his
> own optimization, but this style of programming is getting deprecated
> according to most C++ who basically say "rely on the compiler, optimize
> only as a last minute operation". But here I have an example of what
> would be very unefficient in C/C++ compared to F90:
> 
> > for (i = 0 ; i < n ; i++) {
> >    for (j = 0 ; j < n ; j++) {
> >       a[i][j] = b[i][j] * c[i] ;
> >    }
> > }
> 
> > do j = 1,m
> >   do i = 1, n
> >     a (i,j) = b(i,j) * c(i)
> >   enddo
> > enddo 
> 
[...]

As a physicist programming in C++ I have to compare the performance of my
programs to those written in FORTRAN.
C++ routines written in a FORTRAN _style_ are often slower than the routines
written in FORTRAN.
Nevertheless my programs are faster since I try to avoid loops
as the one mentioned above, hiding the actual calculation in linear
algebra classes in which I call BLAS routines.
And why not using a FORTRAN subroutine in special cases ?

What's really needed, in my opinion, is not a change in the language which enables
the compiler to perform better optimization, but powerful libraries & classes,
e.g. a BLAS class or sophisticated matrix classes (like LAPACK++ (LAPACK+=2 ?) ).

Regards Peter

------------------------------------------------------------

Peter Schmitteckert   ---  Lehrstuhl fuer Theoret. Physik 2
Institut f\"ur Physik ---  D 86135 Uni Augsburg 
e-mail: Peter.Schmitteckert@Physik.Uni-Augsburg.de
URL:    http://www.physik.uni-augsburg.de/theo2/Group/Schmitteckert.html
Phone:  +49-821-5977-246  Fax:  +49-821-5977-262

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