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Aproximation
http://forum.alglib.net/viewtopic.php?f=2&t=104		 Page 1 of 1
Author:  juanraulpj [ Thu Oct 28, 2010 10:27 am ]
Post subject:  Aproximation
I wrote some time ago for help on an approach but I have not got the results I expected. With the function you suggested me to use do not get a really good approximation. Before I try to implement the program with c# I did in MATLAB and approached the curve quite well. I send a picture with what I get with MATLAB and with your spline1dfitcubicwc function. The blue line are the points to align, the red line I get with MATLAB and green which I get from spline1dfitcubicwc function. Thanks in advance.

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Author:  juanraulpj [ Thu Oct 28, 2010 10:29 am ]
Post subject:  Re: Aproximation
I forgot ... I do an analysis of the sections which I have and analyze each section separately
Author:  Sergey.Bochkanov [ Thu Oct 28, 2010 11:54 am ]
Post subject:  Re: Aproximation
Can you describe your problem in more details:
* do you have parametric problem (you try to fit x(t) and y(t) separately) or you try to fit Y as function of X?
* how do you split your data into segments?
Author:  juanraulpj [ Thu Oct 28, 2010 2:25 pm ]
Post subject:  Re: Aproximation
XY points are geographical coordinates (lat lon). This point define the trajectory of a mobile. Data analyzed are not very stable as you can see then what I have to do is bring that information to then represent them in google maps and you're in line (more or less) to the reality of the streets. So I want to approach and no interpolations. If you look at the red line I get with MATLAB is more or less the direction of the street but not exactly.
Author:  juanraulpj [ Thu Oct 28, 2010 2:37 pm ]
Post subject:  Re: Aproximation
To split data into segments I had create a function who analyze the tendence of the curve and after, cut up the curve in segments
Author:  Sergey.Bochkanov [ Thu Oct 28, 2010 4:18 pm ]
Post subject:  Re: Aproximation
Do you have time values assigned to points? I.e. not only x[] and y[], but array of t[] which contain time when points was sampled. With time, it could be much more easier...
Author:  juanraulpj [ Tue Nov 02, 2010 9:04 am ]
Post subject:  Re: Aproximation
Yes... I have 4 data inputs. x[] y[] t[] w[], where w[] are the weights.
Author:  Sergey.Bochkanov [ Tue Nov 02, 2010 9:39 am ]
Post subject:  Re: Aproximation
Maybe you should try parametric fitting? I.e. fit x(t) and y(t) separately, then plot resulting curve. You can use new penalized regression spline fitting functions (described at http://www.alglib.net/interpolation/lea ... #splinefit ).
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