Re: [eigen] matrix::linspace

[Jitse Niesen <jitse@xxxxxxxxxxxxxxxxx>]

On Tue, 26 Jan 2010, Benoit Jacob wrote:

> 2010/1/26 Hauke Heibel <hauke.heibel@xxxxxxxxxxxxxx>:
> > This depends on your application. If you want something like this to work
> >
> > VectorXd x = VectorXd::LinSpaced(-1.0,1.0,10000);
> > std:acos(x(0));
> > std::acos(x(end));
> >
> > it better be in range or you'll end up with NaN when x(0)<-1 or
> > x(end)>-1. But maybe that's too application specific.
>
> I'd call that a problem specific to acos(), not to the problem at hand!

That depends how you define the problem at hand :)

I'd define it as, LinSpaced(start, end, size) returns a vector with 'size' 
elements whose first element is 'start' and last element is 'end' such 
that the distance between consecutive elements is constant up to round-off 
error.

I wonder, in what practical situation is the performance of linspace a 
bottleneck? If there are none - and I cannot think of any - then perhaps 
accuracy is more important than performance.


Jitse