Hello all together,

I have tried to understand as JTS handles with the inaccuracy from doubles. As 
already mentioned there still appear mistakes with my calculations, because 
some values differ around 0.000000000004, although they are same. To solve this 
problem I have carried out some tests with JTS and tried to comprehend. On this 
occasion, I found the following difference between two equal geometrical cases:

1. Fall:

Linestring1:  "LINESTRING(4 1, 4 7)";

Linestring2: "LINESTRING(1 4, 7 4)";

With the intersection „linestring1.intersection(linestring2)“ the point „POINT 
(4 4)“ came out as expected.

The question „linestring1.intersects(linestring1.intersection(linestring2))” 
delivered true.

2.Fall:

Linestring3:  "LINESTRING(-27611.19260069567 25315.392403581718, 
-11080.415853237311 23468.8694690252)";

Linestring4:  "LINESTRING(-21456.11615217394 29272.22726334569, 
-18818.226245664628 18368.948983107195)";

With the intersection „Linestring3.intersection(linestring4)“ the point „POINT 
(-20301.268838372802 24498.858366300974) „ came out.

However the question 
„Linestring3.intersects(linestring3.intersection(linestring4))” returns false.
In fact it should return true? Does one of you know an explanation of this?  
Maybe someone does know who about JTS I can contact or who knows a lot about 
it? Or should I announce this as a bug?

With kind regards,

Anke Trittenbach

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