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| Least sqaure fitting using lslfitlinear(...) http://forum.alglib.net/viewtopic.php?f=2&t=578 |
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| Author: | christian_blesing [ Mon May 14, 2012 6:50 pm ] |
| Post subject: | Least sqaure fitting using lslfitlinear(...) |
Hi, I'm a complete newbie with ALGIB, so sorry for this post. i want to fit Data from a laser scanner to a elliptical function like this: A*x?+B*x*y+y? + 1 = 0 My laser scanner interface gives points(x/y). For this task i want to use the lslinearfit(...) method. But i'm confused about the function parameter. The first one called "y" is the experimental data array but how do i arrange the x/y value pairs in this 1d array? The second parameter "fmatrix" should be a matrix of basis functions calculated at sample points. In my case i only got one... How many sample points i have to calculate? I Hope someone can help me with it. Many Thanks |
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| Author: | Ray [ Wed Jun 20, 2012 10:01 pm ] |
| Post subject: | Re: Least sqaure fitting using lslfitlinear(...) |
Hello christian_blesing! Did you solved your problem? I have simmilar problem. I'm using triangulation laser, so I move this Laser along the x-axis and measure the distance to a cylinder. As result I get a profile of the cylinder, that means I get points that can be fitted by a circle function. I tried the nonlinear fitting using func=sqrt(r^2-(x-x_m)^2)+y_m, but without usable results. |
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| Author: | Ray [ Fri Jun 22, 2012 7:23 pm ] |
| Post subject: | Re: Least sqaure fitting using lslfitlinear(...) |
Choosing func=(x-x_m)^2+(y-y_m)^2-r^2 it works very good. |
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| Author: | christian_blesing [ Sat Jun 23, 2012 11:45 am ] |
| Post subject: | Re: Least sqaure fitting using lslfitlinear(...) |
hey Ray, thx for your relpy! I have not solved the problem completly yet, but it works acceptable with many additional filters to locate the false detected elliptical parts. I use the function lsfitlinear() and put my scanner values (x,y) as sample data into the function. Now the current scan segment is testet with the sample data. I dont know if there is a better way to use this funktion. I've read things that you can giva a function like f(x)= x?+2xy.... to the lsfitlinear() function. Maybe this would work better as use the sample data in (x,y) form. viewtopic.php?f=2&t=588 in this topic i have discribed the problem. As you can see i detect a lot of straight lines ..... maybe you can help me how you put the func=(x-x_m)^2+(y-y_m)^2-r^2 to the alglib method? many thanks christian |
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| Author: | Ray [ Sun Jun 24, 2012 6:54 pm ] |
| Post subject: | Re: Least sqaure fitting using lslfitlinear(...) |
Hey! I'm not sure, if I understood your pictures, but here you can see how I made it with my problem: viewtopic.php?f=2&t=591 Please look at the file main1 and not at main. There the issue is explained well and with the Help of mr. Bochkanov it works well too. I hope it will be a Help. And if there are still questions, please ask me :-). |
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| Author: | Ray [ Sun Jun 24, 2012 7:20 pm ] | |||
| Post subject: | Re: Least sqaure fitting using lslfitlinear(...) | |||
Hey here is the already corrected version. The comments in the code are partially in german , but if you look in the link I posted before, there the comments are completely in english.
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