# XlXtrFun Extra Functions

(5/2)

### Description

XlXtrFun™ Extra Functions for Microsoft Excel

Three Dimensional Interpolate and Extrapolate Functions; Two Dimensional Interpolate, Extrapolate, Cubic Spline, Polynomial Curve Fitting, Line Intersections, Minima, Maxima, First Derivative, Second Derivative, and other functions.Free download.

XlXtrFun.xll is a collection of functions which extends the capabilities of Microsoft Excel; developed primarily to facilitate, interpolation of 2-dimensional and 3-dimensional data, and simplify 2-variable curve fitting. XlXtrFun has been used for years by engineering and research and development personnel on every continent who need to interpolate, extrapolate, and curve fit data rapidly, reliably, and with a virtually non-existent learning curve.

If you work with real-life data and want to interpolate, extrapolate, or curve fit, then you will find these functions very useful.

Calculation Reference
http://www.xlxtrfun.com/XlXtrFun/XlXtrFun.htm

### Calculation Preview

04 Nov 2014
File Size: 738.13 Kb
File Version: 1.0
File Rating (5/2)

Full download access to any calculation is available to users with a paid or awarded subscription (XLC Pro).
Subscriptions are free to contributors to the site, alternatively they can be purchased.
johndoyle[admin] 9 years ago
Update to my earlier comment: I used to use the Xlxtrfun addin regularly but I have stopped using it since moving to a 64 bit version of Excel (the Xlxtrfun addin is not compatible with the 64 bit version). These days I use the trendline features within Excel, there is an [article describing this approach with video help files too](/404).
The trendline method described in the article is a better approach as it only uses Excel native functions. I hope this is a good solution for you.
johndoyle[admin] 10 years ago
I don't think the addin works for 64 bit versions of Excel. I have used this a lot in the past but these days I prefer using Excel's native trendlines and equations. There is an [explanatory video](https://www.youtube.com/watch?v=X_sZFWwOHPQ&index=4&list=PLCF7BA14E14C11993) here.
johndoyle[admin] 10 years ago
This used to be a link to the XlXtrFun site but it appears not to be working anymore. It can be downloaded here now. Thank you Brian Wetzelfor reporting this in.