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Anke Trittenbach
Thank you Matthias for the information, these have helped me already a lot.

Now I have tried about a PrecisionModell that the Linestrings intersect the generated Point of the Intersection. The PrecisionModell was set that the geometries had no decimal places. However, this time the Linestrings do not intersect the point from the intersection. I thought the PrecisionModel is for such problems?!

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Sunburned Surveyor
Anke,

I think you might be trying to push your computer beyond the limits of
reasonable floating point number arithmetic. I don't have the
expertise in this subject that other programmers on this list do, but
I would recommend the following:

- Read a little bit about floating point numbers and how they work. I
have actually found the wikipedia page has the info that is easiest to
understand.

- Set up your code to test for results within a certain tolerance. For
example: Don't compare exact coordinate values, but see if coordinate
values are within a range. Don't ask if two coordinates are exactly
the same, but rather if they fall within a bubble of some given
radius. The same thing can be done if you want to know if a coordinate
falls on a line. Don't ask if the point is exactly on the line, but if
it falls within a given buffer of the line.

At some point, the errors get so small they don't matter. If they do
matter, then you need to use something besides floating point numbers,
and that makes your math a lot slower. :]

If you are morbidly interested, I started work on some code that
allowed the client code to set the level of precision for arithmetic
calculations. A person could set up a geometry library using this code
with their required level of precision. I never got that far with my
experiment, but that was my eventual goal. I was always curious just
how much slower it would be. :]

The Sunburned Surveyor

On Tue, May 26, 2009 at 5:28 AM, Anke Trittenbach
<[hidden email]> wrote:

> Thank you Matthias for the information, these have helped me already a lot.
>
> Now I have tried about a PrecisionModell that the Linestrings intersect the generated Point of the Intersection. The PrecisionModell was set that the geometries had no decimal places. However, this time the Linestrings do not intersect the point from the intersection. I thought the PrecisionModel is for such problems?!
>
> --
> Neu: GMX FreeDSL Komplettanschluss mit DSL 6.000 Flatrate + Telefonanschluss für nur 17,95 Euro/mtl.!* http://portal.gmx.net/de/go/dsl02
> _______________________________________________
> jts-devel mailing list
> [hidden email]
> http://lists.refractions.net/mailman/listinfo/jts-devel
>
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