Boost logo

Boost :

From: rogeeff (rogeeff_at_[hidden])
Date: 2001-12-06 13:26:09


--- In boost_at_y..., Ullrich Koethe <u.koethe_at_c...> wrote:
> rogeeff wrote:
> >
> > >
> > > [As an aside: it would be really helpful for testing if there
were
> > some
> > > support for determining the right tolerance for floating point
> > > comparisons automatically on every platform, depending on the
> > expected
> > > error of the computation. Would this be part of your module?]
> >
> > This is already in place.
>
> Ah sorry, I hadn't seen this new page in the docu. Now I see that
the
> float comparison code can really be refactored into a separate
header,
> so that it can be used in other contexts than testing

> Some remarks:
>
> * an output "[1 != 1 (1e-08)]" isn't very helpful. You should
control
> the output precision of the floats so that the difference can be
seen
> (in the example "[1.00000001 != 1.00000002 (1e-08)]")

I will try though I am not sure that it will possible in any case.

> * there are a few errors in the examples (e.g. e-11 instead of e-10)

OK

> * also in the examples: what does "1 /* really 2 */ " mean? Why
does the
> resulting error message say that the tolerance was 1e-05 when it
> actually was 1?

1 and 2 are the number of arithmetic operation. See second form of
marcos.

> * are enough compilers supporting numeric_limits to require its
> existence?

? Does anybody know the answer on this question?

>
> * you should document more clearly your modification of Knuth's
> algorithm. What are you doing differently, why was this necessary
and
> why does it work? (This is hard to guess from the code).

I will try.

>
> Ulli
>
> --
> ________________________________________________________________
> | |
> | Ullrich Koethe Universität Hamburg / University of Hamburg |
> | FB Informatik / Dept. of Computer Science |
> | AB Kognitive Systeme / Cognitive Systems Group |
> | |
> | Phone: +49 (0)40 42883-2573 Vogt-Koelln-Str. 30 |
> | Fax: +49 (0)40 42883-2572 D - 22527 Hamburg |
> | Email: u.koethe_at_c... Germany |
> | koethe_at_i... |
> | WWW: http://kogs-www.informatik.uni-hamburg.de/~koethe/ |
> |________________________________________________________________|


Boost list run by bdawes at acm.org, gregod at cs.rpi.edu, cpdaniel at pacbell.net, john at johnmaddock.co.uk