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fitting circle to data
From: |
Gastón Araguás |
Subject: |
fitting circle to data |
Date: |
Mon, 30 Nov 2009 16:46:55 -0300 |
Hello,
i need to extract the radius and centre points of a circle fitting a
set of datas. I was trying with this way
xt = %data
yt = %data
F = @(x,p) sqrt( p(3).^2 -(x-p(1)).^2)+p(2)
pin = [1;1;1]
[f, p] = leasqr(xt,yt,pin,f);
testing it with xt = 2+4*cos(thetas) and yt = 3+4*sin(thetas) works well, i get
p =
2.0000 + 0.0000i
3.0000 + 0.0000i
4.0000 - 0.0000i
but using the real data i get
p =
-2.23630 - 0.62042i
12.24122 - 64.02140i
0.34923 + 59.63389i
and should be aprox. p = [0, 300, 290]
If i use pin = [0; 300; 290] get
p =
-2.2316 - 1.5828i
12.2604 - 162.9057i
0.3318 + 161.1838i
is that right? how souhld i use this comples result?
Thank you
PD: here a few xt and yt datas
xt =
29.94340
28.45820
27.19490
25.85900
24.73510
23.54580
21.88660
19.90880
17.77030
15.64780
13.04540
10.67190
8.43594
6.35659
4.31690
2.28645
0.19964
-1.74150
-3.66550
-5.75025
-7.75397
...
yt =
13.277
13.079
12.952
12.747
12.670
12.638
12.475
12.225
12.059
11.977
11.773
11.676
11.556
11.526
11.454
11.415
11.394
11.449
11.444
11.491
11.556
...
--
Gastón Araguás
______________________________________________________
CIII - Centro de Investigación en Informática para la Ingeniería
Univ. Tecnológica Nacional Facultad Regional Córdoba. Argentina
- fitting circle to data,
Gastón Araguás <=