Tarsier Tools
Linear Interpolation Function
Overview
Designed for OpenOffice.org Calc and Microsoft Excel, this "Tarsier Tool" interpolates between consecutive ordered points from the given data. The function can be configured to interpolate using either a step or linear function. If the input value is outside of the range of the X coordinates the function can be configured to either perform a linear extrapolation using the two nearest points; return a constant value of the nearest value or return the Excel #Num value.
Please note that this Tarsier tool is distributed with NO WARRANTY.
This page contains the following information on this Tarsier Tool.
Usage Instructions
License Fee
How to Install
How to Uninstall
Revision History
Software for Download
Source Code
Technical Support
Further Information
Usage Instructions To use the Linear Interpolation Function:
The following instructions assume you know how to use functions in Calc or Excel. In Excel my linear interpolation function can be found either under the "All" or under "User defined" in the function menu, but in Calc you will have to type the function name.
The function has three mandatory arguments and two optional arguments.
You must;
The known X values must be in numerical order, minimum to maximum.
How to specify the result calculated by the function The values in the Example result column are calculated using the following data.
License Fee This "Tariser Tool" is licenced under the Creative Commons AttributionNonCommercialShareAlike 4.0 International License. There is no license fee for personal use of this tool. However, if you are using this software within software that you are developing and intend to sell, please email me for details of the license fee.
How to Install Instructions for OpenOffice.org Calc (version 4) Will work for LibreOffice 3
Instructions for Microsoft Excel
How to Uninstall Instructions for OpenOffice.org Calc (version 4) work for LibreOffice 3
Instructions for Microsoft Excel
Revision History
Software for Download
Technical Support
Frequently Asked Questions Currently there are no FAQ for this tool. If you have a question, please email it to me. Please ensure that you identify that the question is about my Linear Interpolation Function (TT03002).
Bug Reports If you suspect a bug in this Tarsier Tool, before contacting me, please check the FAQs and Bug Reports to see if it has already been identified. If it hasn't, email me a description. Please ensure you identify the Tarsier Tool, (Linear Interpolation Function TT03002), the operating system and spreadsheet program in the email and include as much detail as possible; including a simple example application is always helpful! but make sure it does not contain proprietary or confidential information.
Currently there are no reported bugs for this Tarsier Tool.
Further Information This section will be updated with links to information relating to the principles behind and the uses of this Tarsier Tool, as I become aware of them.
Please note that this Tarsier tool is distributed with NO WARRANTY.
This page contains the following information on this Tarsier Tool.
Usage Instructions
License Fee
How to Install
How to Uninstall
Revision History
Software for Download
Source Code
Technical Support
Further Information
Usage Instructions To use the Linear Interpolation Function:
The following instructions assume you know how to use functions in Calc or Excel. In Excel my linear interpolation function can be found either under the "All" or under "User defined" in the function menu, but in Calc you will have to type the function name.
The function has three mandatory arguments and two optional arguments.
You must;
 specify the range of cells containing the known X values, (argument known_x)
 specify the range of cells containing the known Y values, (argument known_y)
 specify the X value you are interpolating against, (argument x_Value)
With this information the function will perform linear interpolation to find the specified value, or extrapolate to find the Y value if the X value is outside the range of known X values.
Additionally, you can specify the following options;
 what value should be returned if the X value interpolated against is outside the range of known X values, (argument cutOffAction, 0 = extrapolate; 1 = cut off at the nearest known value, 2 = return #NUM! or 999 in Calc)
 use step interpolation, (argument step, a binary value, false = perform linear interpolation, true = perform stepwise interpolation)
The known X values must be in numerical order, minimum to maximum.
How to specify the result calculated by the function The values in the Example result column are calculated using the following data.
Description  x_value  cutOff  step  Example formula (Excel Calc)  Result 
Compulsory arguments  within X value range  1.5  Not specified  Not specified  =LinearInterpolator($A$2:$A$7,$B$2:$B$7,1.5)  2.7 
Compulsory arguments  outside X value range  1.0  Not specified  Not specified  =LinearInterpolator($A$2:$A$7,$B$2:$B$7,1.0)  0.5 
6.0  Not specified  Not specified  =LinearInterpolator($A$2:$A$7,$B$2:$B$7,6.0)  35.5  
Cut off if outside X value range  1.0  1  Not specified  =LinearInterpolator($A$2:$A$7,$B$2:$B$7,1.0,1)  0.8 
6.0  1  Not specified  =LinearInterpolator($A$2:$A$7,$B$2:$B$7,6.0,1)  26.0  
Return error if outside X value range  1.0  2  Not specified  =LinearInterpolator($A$2:$A$7,$B$2:$B$7,1.0,2)  #NUM! 
6.0  2  Not specified  =LinearInterpolator($A$2:$A$7,$B$2:$B$7,6.0,2)  #NUM!  
Stepwise interpolation  within X value range  1.5  0, 1, 2  True  =LinearInterpolator($A$2:$A$7,$B$2:$B$7,1.5,0,True)  1.1 
2.001  0, 1, 2  True  =LinearInterpolator($A$2:$A$7,$B$2:$B$7,2.001,0,True)  4.3  
3.9999  0, 1, 2  True  =LinearInterpolator($A$2:$A$7,$B$2:$B$7,3.9999,0,True)  9.9  
Stepwise interpolation  outside X value range  1.0  0  True  =LinearInterpolator($A$2:$A$7,$B$2:$B$7,1.0,0,True)  0.8 
6.0  1  True  =LinearInterpolator($A$2:$A$7,$B$2:$B$7,6.0,1,True)  26  
4  2  True  =LinearInterpolator($A$2:$A$7,$B$2:$B$7,4.0,2,True)  #NUM! 
Note, constant values shown in the example equations above can of course be replaced by cell references, definitions, etc...
Error Messages
When using the Linear Interpolation Function, it will return an error code in the following circumstances;
Description  Calc  Excel  
1. 

999  #Num 
2.  The specified cutoff is invalid, i.e. not in the range 0 to 2.  997  #N/A 
License Fee This "Tariser Tool" is licenced under the Creative Commons AttributionNonCommercialShareAlike 4.0 International License. There is no license fee for personal use of this tool. However, if you are using this software within software that you are developing and intend to sell, please email me for details of the license fee.
How to Install Instructions for OpenOffice.org Calc (version 4) Will work for LibreOffice 3
Instructions for Microsoft Excel
How to Uninstall Instructions for OpenOffice.org Calc (version 4) work for LibreOffice 3
Instructions for Microsoft Excel
Revision History
Rev  Date  Description 
1.0  26Aug15  Initial Version Released, based on Rev 1.0 of my Excel version 
Rev  Date  Description 
1.0  10Nov03  Initial Version Released 
Software for Download
OS Ver.  Spreadsheet  Software 
OS X 10  Apache OpenOffice™ 4 Calc  tt03002.ods (11.7k) 
Ubuntu 12.04  LibreOffice 3  
Win 2000  Excel 97  TT03002.xla (37.9k) 
Win XP Pro  Excel 2003  
Win 7  Excel 2007 
Please let me know if you have used my Linear Interpolation Function, successfully or not, on any other Operating System and spreadsheet combination.
Source Code In accordance with the GNU General Public License the Microsoft Excel Addin used to distribute this Tarsier Tool is not password protected allowing you to view and modify it if you require. You should review the GNU GPL to determine your rights to distribute this software and be informed that this software is distributed with NO WARRANTY.Technical Support
Frequently Asked Questions Currently there are no FAQ for this tool. If you have a question, please email it to me. Please ensure that you identify that the question is about my Linear Interpolation Function (TT03002).
Bug Reports If you suspect a bug in this Tarsier Tool, before contacting me, please check the FAQs and Bug Reports to see if it has already been identified. If it hasn't, email me a description. Please ensure you identify the Tarsier Tool, (Linear Interpolation Function TT03002), the operating system and spreadsheet program in the email and include as much detail as possible; including a simple example application is always helpful! but make sure it does not contain proprietary or confidential information.
Currently there are no reported bugs for this Tarsier Tool.
Further Information This section will be updated with links to information relating to the principles behind and the uses of this Tarsier Tool, as I become aware of them.
Copyright ©2003 Tarsier Software Solutions Creative Commons AttributionNonCommercialShareAlike 4.0 International License