Curve Fitting Models-Excel 1

[bonzoboy]

Does anybody have a source of good curve fitting tools that could be used in Excel (or similar). I have Table Curve 2D and 3D, but not for the most recent version of Windows, and as such, I can't use them (despite their ease of use).

Any ideas out there (i.e. without paying $500...again).

 

[Denial]

This question comes up from time to time in the "Engineering Spreadsheets" forum (and elsewhere). See, for example, threads:
724-97493
770-82803
770-142106

If you need to do a lot of curve fitting, a specialised tool would be best. If your need is either only occasional or particularly exotic, then Excel can probably do the job (but at a cost of considerably more time for each curve).

 

[corus]

Excel already has curve fitting tools such as polynomials and log. If you want more specialised fitting curves such as trigonometric curves then look at the basics of least squares regression and derive the coefficients you'll need from first principles.

corus

 

[m777182]

An extension to Corus:... and Fourier transformation.
m777182

 

[PNachtwey]

Look at the LINEST function. It can do a lot more than just linear equations. I can find the coefficients of polynomials and non-linear equations too. I think LINEST is an add on so you may have to install it off your Office CD.

 

[powerjunx]

guys,

I heard about minitab and mathcad. Do this have curve fitting features?

 

[IRstuff]

mathcad -- yes

TTFN

 

[GregLocock]

Minitab can do it, but I can't remember if it is painless or just easy.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[corus]

I found a site that can do curve fitting for more diffciult data. It's on NLREG.com. The price is $140 but you can download a trial version for 30 days, allowing only 50 data points. Failing that, try

http://www.eurometros.org/

which has lots of free curving fitting algorithms in either excel, fortran, or matlab etc.

corus

 

[BronYrAur]

I don't do much curve fitting, but I have had a lot of luck with a program called CurveExpert1.3

You can download it here:

http://curveexpert.webhop.biz/

 

[BronYrAur]

The website i just posted looks like it may charge you to download, but i am positive that i downloaded it for free. I'm sure it's out there somewhere

 

[FOETS]

Minitab does have curve fitting and its real simple to do

 

[MrMask]

You could use Origin from OriginLab (

http://www.originlab.com).

It is pretty good for fitting, with many built-in models or use-defined models