[Answered] Perimeter of an ellipse

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Panchdara
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[Answered] Perimeter of an ellipse

Post by Panchdara » Sat Sep 05, 2020 8:29 pm

Question: I just watched a neat video on the perimeter length of an ellipse. What formula/approximation does QCAD use?

Best
Last edited by Panchdara on Sun Sep 06, 2020 9:09 am, edited 1 time in total.
QCAD 3.26.0 / Windows 10 2004 x86_64

CVH
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Re: Perimeter of and ellipse

Post by CVH » Sat Sep 05, 2020 8:51 pm

Hi,
Ellipse are indeed the tougher ones among the entities.
There aren't closed form solutions.
Talking about perimeter length, what about the others properties ... :wink:
Intersections ... Point on ...

Well, I would not know.
Andrew can tell you that.

So, I keep lurking. :wink:

Regards,
CVH

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andrew
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Re: Perimeter of and ellipse

Post by andrew » Sat Sep 05, 2020 9:03 pm

QCAD uses Simpson's Rule as approximation for ellipse arc lengths.

CVH
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Re: Perimeter of and ellipse

Post by CVH » Sun Sep 06, 2020 6:01 am

Thankx
CVH

Panchdara
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Posts: 154
Joined: Wed Nov 25, 2015 4:15 pm

Re: [Answered] Perimeter of an ellipse

Post by Panchdara » Sun Sep 06, 2020 9:16 am

Yes, thanks Andrew. Number of iterations? Or is that dependent on particular setup/specifics of the drawing (such as ellipse ratio)? (I think if I tried to read the code, it'd be like looking for a needle in a haystack :D )

I am just curious as I had just watched an entertaining video on the subject.

Best regards
Hugh
QCAD 3.26.0 / Windows 10 2004 x86_64

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