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mohamed1986
43 Posts |
 Posted - 01/26/2015 : 08:23:54 AM
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Origin Ver. and Service Release (Select Help-->About Origin): 9.1
Operating System:win. 7
Dear friends,
I fitted my data to a circle to appear as shown in the figure.
Now I need to extrapolate the fitting to the x-axis, and get the value of the angle between the x-axis and the radius of the circle arc crossing this axis as in the following picture.
Thanks much
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lkb0221
China
497 Posts |
Posted - 01/26/2015 : 10:07:40 AM
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The angle will be asin(yc / r).
coordinate of intercept on X will be x1 = xc+sqrt(r^2-yc^2) and x2 = xc-sqrt(r^2-yc^2).
You can add them as derived parameters in your fitting function so next time you fit your data, they will be calculated automatically. |
Edited by - lkb0221 on 01/26/2015 10:22:22 AM |
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mohamed1986
43 Posts |
Posted - 01/26/2015 : 11:55:47 AM
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Thanks much sir for your kind help.
Is the expression for the angle written correctly ??
"The angle will be asin(yc / r)."
As it appears to be a negative value to me after the fitting.
Is it possible to extend the fitted curve to extrapolate the x-axis?
Thanks much |
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lkb0221
China
497 Posts |
Posted - 01/26/2015 : 12:02:19 PM
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That's just a matter of direction, since your yc is negative. Please use abs(yc) instead.
Anyway, it's just basic analytic geometry, you can figure it out.
For fitting curve range, please go to NLFit dialog, Settings tab, Fitted Curves page, Fitted Curve Plot branch, Data Type of x sub-branch, range option. |
Edited by - lkb0221 on 01/26/2015 12:05:29 PM |
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mohamed1986
43 Posts |
Posted - 01/26/2015 : 12:29:36 PM
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Thanks much sir for your kind help.
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Extrapolation of circle fitting.