| Author |
 Topic  |
|
|
iggboert
Germany
7 Posts |
 Posted - 10/28/2008 : 09:51:07 AM
|
Prog: Origin 8G SR1
OS: WinXP
Hello, I have some x/y-values and want to describe a geometric best-fit-circle in it. The curve looks nearly like a quarter circle.
I found lots of possibilities to make a linear fit (or NLFit). But i could not find any option to describe a best-fit-circle.
Is it anyhow possible to it? Or is it not possible with Origin?
Is it possible by writing a new function? If yes, please give me a hint.
Regards
iggboert from Erlangen/Germany |
|
|
liuxiaopi
China
Posts |
Posted - 10/31/2008 : 04:30:22 AM
|
If it is just one quarter of a circle: (x-xc)^2+(y-yc)^2=r^2, please try defining the following fitting function: y-yc= +/-sqrt(r^2-(x-xc)^2), where yc, xc, r are parameters. The sign +/- can be chosed according to your data, i.e: + for upper circle, - for lower circle. xc,yc can be set to zero or none if reasonable.
In case it is more like an ellipse: (x-xc)^2/a^2+(y-yc)^2/b^2=1, please try defining the following fitting function:
y-yc = +/-b*sqrt(1-(x-xc)^2/a^2). The sign can be chosed similarly.
Hope this helps
Jack |
Edited by - liuxiaopi on 10/31/2008 04:32:34 AM |
 |
|
|
iggboert
Germany
7 Posts |
Posted - 11/07/2008 : 04:18:44 AM
|
Thanks a lot for helping me.
I successfully implemented the function.
Regards |
|
|
| |
Topic |
|
|
|
Best-Fit-Circle