Why is this two line disjoint

[KM_Yotsuha]

those two line's intersectresult is disjointed，why is that?

debug result:

the dwg file is in attachment

[jeremy_tammik · Accepted solution]

Maybe they only just touch, and floating point inaccuracies cause the algorithm to report disjunct. Maybe you will get a result that better matches your specific requirements by determining the distance from the vertical line's endpoints to the horizontal line. Maybe the distance of the bottom one is very small, but non-zero. Maybe it will help for you to check out the recent repetition of the need for fuzz:

https://thebuildingcoder.typepad.com/blog/2022/08/instances-in-room-and-need-for-fuzz.html#3