Two programs are included: XlXtrFun and SurfGen.
(In addition, there are files useful only to programmers who want to export the functions to other programming languages.)


XlXtrFun contains functions that look intrinsic to Excel. These functions are primarily interpolating and curve fitting, and include both two-dimensional (2D) and three-dimensional (3D) interpolating.

The two 3D interpolate functions in XlXtrFun, Interp3D and InterpMatrix, require the data to be in groups of constant Xs. For example, suppose you have a data set of the elevation above sea level for 1,000 locations for a given area of some planet, say, Earth. If the 3D data collected was along lines of constant longitude or lines of constant latitude, then you can use XlXtrFun's Interp3D function.

SurfGen (Surface Generation from Scattered Input Data)

If you have (X,Y,Z) data that cannot readily be put into groups of constant Xs, use SurfGen (Surface Generation from Scattered Input Data) to generate data in the format that can be used by XlXtrFun's Interp3D and InterpMatrix functions. SurfGen is not part of XlXtrFun (and therefore does not appear as an intrinsic Excel function). Because the procedure to generate a surface from scattered 3D data takes up to a second to run, a spreadsheet with many cells containing calls to such a time-consuming function would recalculate painfully slowly.


486DX PC or above.
Sufficient for Windows.
Disk Space:
0.5 MB
Operating System:
Windows 95, 98, Me, NT 3.51, NT 4.0, 2000, XP.
Other Software:
Microsoft Excel for Windows 95/97/2000/XP.
However, Microsoft Excel is not required if you are using only the exported functions.


  1. Exit (shut down, quit, stop) Excel.
  2. Unzip XlXtrFun.zip.
  3. Put XlXtrFun.xll wherever you want and use Excel's Add-In Manager to install XlXtrFun.xll.
    1. Start Excel.
    2. If a workbook is not already showing, open or create a new workbook.
    3. Click on Tools - Add-Ins - Browse to wherever you put XlXtrFun.xll - OK - OK.

    OR ...

    Put XlXtrFun.xll in the sacred location listed below.
That's it. The functions should be available whenever you are running Excel. Until you get used to them, use Insert-Function, or the Paste Function button. They will be in the Engineering Function Category and the Low Level I/O Function Category.

I also recommend putting the help files, XlXtrFun.hlp and XlXtrFun.cnt, in the sacred locations listed below, but this is not necessary for XlXtrFun to work.

More Installation notes (if you experienced any difficulties)

Excel thinks everything in XlStart is an Excel file and attempts to open whatever it finds there. Therefore,




XlXtrFun.xll    (This is the only file actually required)

XlXtrFun.hlp, XlXtrFun.cnt

Excel 95



Excel 97

Program Files\Microsoft Office\Office\XlStart

Program Files\Microsoft Office\Office\

Excel 2000
NT 4.0

Application Data\Microsoft\Excel\XlStart

Program Files\Microsoft Office\Office\

Excel 2000
Windows Me

Windows\Application Data\

Program Files\Microsoft Office\Office\

Excel 2000
Windows 2000

Documents and Settings\
UserName\Application Data\Microsoft\Excel\XlStart

Program Files\Microsoft Office\Office\

From an Italian User...


WinXp Pro Italian Sp1
Office 2000 Premium italian

C:\Documents and Settings\UserName\Dati applicazioni\Microsoft\Excel\XLSTART


INSTALLATION OF SurfGen (Surface Generation from Scattered Input Data)

  1. Install XlXtrFun.xll as described above.
  2. Put SurfGen.dll in your path, e.g, C:\Windows\System32.
  3. Put SurfGen.xls wherever you want. It will never be seen by the user. I recommend putting it in C:\Program Files\Microsoft Office\Office (The only consideration is that there is a button on the xlt that is linked to a macro in SurfGen.xls, and it makes things easier if all potential users have SurfGen.xls in the same location.)
  4. Surface Generation from Scattered Input Data.xlt is a template. This is the file you will actually see and use. Put it in the folder that has your other Excel templates, and it will be available to you whenever you do File - New. (Alternatively, you can put it in the folder specified in Tools - Options - General - Alternate startup file location or the same folder as XlXtrFun.xll.)
  5. Button Link: There is a button in Surface Generation from Scattered Input Data.xlt that is linked to a macro in SurfGen.xls. Right now, the button assumes that SurfGen.xls is in C:\Program Files\Microsoft Office\Office. If you put SurfGen.xls in C:\Program Files\Microsoft Office\Office in step 2 above, you are done. If not, you will need to,
    1. Open Surface Generation from Scattered Input Data.xlt as a TEMPLATE (not just as an xls, but as an xlt. Check the title bar at the top of your Excel window. It should read, "Microsoft Excel - Surface Generation from Scattered Input Data.xlt").
    2. Edit - Links and change the source file to wherever you put SurfGen.xls in step 2 above. Save Surface Generation from Scattered Input Data.xlt.

To use: File - New - Surface Generation from Scattered Input Data

Advanced Systems Design and Development

346 Atlantic Avenue
Red Lion, PA 17356
email: support@xlxtrfun.com

Copyright © 2005 by Advanced Systems Design and Development. All rights reserved.
All specifications subject to change without notice.
XlXtrFun is a trademark of Advanced Systems Design and Development.
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