Category Archives: Maths

Charts for discussion

Posted on 24/02/2011 by dougaj4

See the comment from Georg Ströhlein under 2D Spline Interpolation with ALGLIB Here are the charts referred to:

Posted in Charts, Excel, Maths, Newton | Tagged , | 1 Comment

ALGLIB linear and polynomial fitting functions

Posted on 17/02/2011 by dougaj4

As promised here: Fitting high order polynomials this post presents details of four Excel User Defined Functions (UDFs) linking with ALGLIB functions for least squares fitting of linear and polynomial functions.  The new functions are: AL_Linest: AL_LinestCW: AL_PolyFit: and AL_PolyFitCW: These functions have been added … Continue reading →

Posted in AlgLib, Excel, Maths, Newton, UDFs, VBA | Tagged , , , , , , | 5 Comments

Fitting high order polynomials

Posted on 04/02/2011 by dougaj4

This post is a follow up to Using LINEST for non-linear curve fitting and the following comments from Scott Rogers and Lori Miller.  Scott found that he was getting different results from Linest and the xy chart trend line for polynomials of … Continue reading →

Posted in AlgLib, Charts, Excel, Maths, Newton, UDFs, VBA | Tagged , , , , , , , , | 31 Comments

Using LINEST for non-linear curve fitting

Posted on 19/01/2011 by dougaj4

Update 14 March 2020: See LinEstGap with non-linear functions for the latest version of Linest-Poly with new functions for non-linear curves allowing more convenient input and work with data with gaps errors, and/or hidden lines. Update 28 June 2015:  Also see … Continue reading →

Posted in Charts, Excel, Maths, Newton | Tagged , , , , , | 96 Comments

Evaluating higher order polynomials …

Posted on 17/01/2011 by dougaj4

… and a better solution for quadratics. Having written a better solver for high order polynomials, that raises a few other issues.  The error in the roots found by the RPolyJT was checked by simply substituting each root as the … Continue reading →

Posted in Excel, Maths, Newton, UDFs, VBA | Tagged , , , , , , | 4 Comments