Discover MakerZone

MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi

Learn more

Discover what MATLAB® can do for your career.

Opportunities for recent engineering grads.

Apply Today

Thread Subject:
curvature of circle through three points

Subject: curvature of circle through three points

From: Soumyadip Rakshit

Date: 3 Feb, 2006 10:11:18

Message: 1 of 6

Hi,

Could you please tell me the most efficient way of finding the curvature of
a circle passing through three (non-colinear) points.

Thanks a ton,
Soumyadip.

Subject: curvature of circle through three points

From: Jerome

Date: 3 Feb, 2006 06:50:47

Message: 2 of 6

Hi,

most efficient solution .... well, let me see :

1) Ask your professor

2) Ask a colleague

3) Take a piece of paper. Place your 3 points A,B,C.
Draw bisectrix of AB and BC. Intersection give you the center O. Then
measure OA (or OB, or OC)...

4) Last, read this one :

Adam K., "Fit arc to three points" #, 13 Dec 2005 1:57 am </WebX?50@@.ef1eac5>


Hope this helps
Jérôme

Subject: curvature of circle through three points

From: Jerome

Date: 3 Feb, 2006 06:57:32

Message: 3 of 6

Jérôme wrote:

> Draw bisectrix of AB and BC...

Sorry, should read :

Draw perpendicular to AB passing through its midpoint...

Shame on me...
Jérôme

Subject: curvature of circle through three points

From: joa

Date: 3 Feb, 2006 17:27:55

Message: 4 of 6

http://mathworld.wolfram.com/Circle.html
Eq 30-34
curvature = 1/radius

"Soumyadip Rakshit" <soumyadiprakshit@gmx.net> wrote in message
news:Iu3wAu.BtM@bath.ac.uk...
> Hi,
>
> Could you please tell me the most efficient way of finding the curvature
> of a circle passing through three (non-colinear) points.
>
> Thanks a ton,
> Soumyadip.
>
>

Subject: curvature of circle through three points

From: joa

Date: 3 Feb, 2006 17:46:09

Message: 5 of 6

Because it's Friday.


function k = kfrom3points(xs,ys);

%KFROM3POINTS Calculate curvature of a circle given 3 points

%

% K = KFROM3POINTS(XS,YS)

% Where

% XS holds 3 x values

% YS holds 3 y values

% Then

% K is the curvature of the circle through the points


xs=xs(:); % columnize xs

ys=ys(:); % columnize ys


os = ones(3,1);

ss = xs.^2+ys.^2; % sum of squares


a = det([xs ys os]); % Eq. 31

d = -det([ss ys os]); % Eq. 32

e = det([ss xs os]); % Eq. 33

f = -det([ss xs ys]); % Eq. 34


r = sqrt((d^2+e^2)/(4*a^2)-(f/a)); % Eq. 30

k=1/r; % curvature

Subject: curvature of circle through three points

From: Jerome

Date: 3 Feb, 2006 12:27:03

Message: 6 of 6

joa wrote:

> Because it's Friday.

Doh ! It IS FRIDAY !

Jérôme

Tags for this Thread

No tags are associated with this thread.

What are tags?

A tag is like a keyword or category label associated with each thread. Tags make it easier for you to find threads of interest.

Anyone can tag a thread. Tags are public and visible to everyone.

Contact us