[Numpy-discussion] floating point arithmetic issue
Guillaume Chérel
guillaume.c.cherel@gmail....
Fri Jul 30 07:21:23 CDT 2010
Hi,
Thanks for all your answers and the references (and yes, I have to admit
that I've been a bit lazy with Goldberg's article, though it looks very
thorough).
But as numpy is designed for scientific computing, is there no
implementation of an "exact type"
(http://floating-point-gui.de/formats/exact/) to avoid floating point
issues?
As for the details about my problem, I'm trying to compute the total
surface of overlapping disks. I approximate the surface with a grid and
count how many points of the grid fall into at least one disk. I use the
mod operator in a calculation to find the coordinates of the left-most
point of the grid that falls into a given disk, and I do that for all
disks. I need to use floating point numbers with this modulo operator
because I want the resolution of the grid is arbitrary.
I suppose my explanation might not be very straightforward, so if you
know of another good way to compute the surface of overlapping disks,
I'd be glad to know.
Thanks,
Guillaume
Le 30/07/2010 13:21, Pauli Virtanen a écrit :
> Fri, 30 Jul 2010 19:52:37 +0900, David wrote:
> [clip]
>> Indeed, it is not, and that's expected. There are various pitfalls using
>> floating point. Rational and explanations:
>>
>> http://docs.sun.com/source/806-3568/ncg_goldberg.html
> In case of tl;dr, see also http://floating-point-gui.de/
>
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