Re: [eigen] Feature request for array

[Jinglei Hu <jingleihu@xxxxxxxxx>]

Good to know, thanks. I'm wondering if there will be any performance 
test regarding the array part?

Jinglei

Benoit Jacob wrote:
> So, exactly as Rohit says, we have a segment() function for that:
>
>   A.segment(first,size) = B.segment(first,size) + C.segment(first,size);
>
> so for 4..10 you would use segment(4,7).
>
> http://eigen.tuxfamily.org/dox/classEigen_1_1MatrixBase.html#a4d9f2188195e410a09ea180032d6b9a1
>
> Benoit
>
> 2010/1/8 Jinglei Hu <jingleihu@xxxxxxxxx>:
>   
> > Exactly, "slicing".
> >
> > Really cool to have such function. And if its performance can be comparable
> > to Fortran, it would be very attracting.
> >
> > Jinglei
> >
> > Aron Ahmadia wrote:
> >     
> > > Dear Jinglei,
> > >
> > > I think so too, also, the word you are looking for is 'slicing'.
> > > Stencil refers usually to the discretization of a differential
> > > operator, which when performed on a finite difference/finite element
> > > discretization, usually refers to a local slice of your array around
> > > the evaluation point.
> > >
> > > HTH,
> > > A
> > >
> > > On Fri, Jan 8, 2010 at 10:06 AM, Rohit Garg <rpg.314@xxxxxxxxx> wrote:
> > >
> > >       
> > > > I think this can be done TODAY in eigen using segments.
> > > >
> > > > 2010/1/8 Jinglei Hu <jingleihu@xxxxxxxxx>:
> > > >
> > > >         
> > > > > Hi,
> > > > >
> > > > > Eigen is really a nice piece of work. Thanks!
> > > > >
> > > > > In scientific computing, one and two (or even higher) dimensional arrays
> > > > > are
> > > > > widely used. It would be nice to have the following function:
> > > > >
> > > > > 1dArray A(10), B(10), C(10);
> > > > > A(4:10) = B(4:10) + C(4:10);
> > > > >
> > > > > I do not know the professional term for this, maybe stencil? In fortran,
> > > > > this function for array is built-in. Blitz++ provides such function for
> > > > > array and claimed performance in par with fortran. How about
> > > > > incorporating
> > > > > this staff in Eigen?
> > > > >
> > > > > Cheers,
> > > > > Jinglei
> > > > >
> > > > >           
> > > > --
> > > > Rohit Garg
> > > >
> > > > http://rpg-314.blogspot.com/
> > > >
> > > > Senior Undergraduate
> > > > Department of Physics
> > > > Indian Institute of Technology
> > > > Bombay
> > > >
> > > >
> > > >
> > > >
> > > >         
> > >
> > >
> > >       
> >
> >
> >     
>
>
>
>