ALGLIB forum
It is currently Fri May 24, 2024 5:15 am

All times are UTC

Forum rules

1. This forum can be used for discussion of both ALGLIB-related and general numerical analysis questions
2. This forum is English-only - postings in other languages will be removed.

Post new topic Reply to topic  [ 2 posts ] 
Author Message
 Post subject: LSFitLinear: cubic interpolation
PostPosted: Mon May 31, 2010 10:26 pm 

Joined: Mon May 31, 2010 10:13 pm
Posts: 1
I'm a newbie with ALGLIB
I'm using a0*x^3+a1*x^2+a2*x+a3 to interpolate data values with LSFitLinear:
x y
46 68
70 120
94 138
95 145
102 165
120 205
I notice wrong result and I have solved the problem scaling input by dividing by 100. What I do wrong?



 Post subject: Re: LSFitLinear: cubic interpolation
PostPosted: Thu Jun 03, 2010 7:22 pm 
Site Admin

Joined: Fri May 07, 2010 7:06 am
Posts: 915
Looks like your problem has very bad condition number. Scaling makes it less apparent but doesn't solve.

I think that right solution is to use Chebyshev polynomials for fitting, than convert to power basis. I'll include this code in the next release of ALGLIB.

Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 2 posts ] 

All times are UTC

Who is online

Users browsing this forum: Bing [Bot] and 1 guest

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group