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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.
Posted with the kind permission of: Advanced Systems Design and Development
Free, download now
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.
"There is a great satisfaction in building good tools for other people to use."
Freeman Dyson (b. 1923); British-born U.S. physicist, author.
From a user in Minano, Italy: "Your functions have become very popular in the last two or three years, and it would be tough to abandon them."
Using Spline(), Interpolate(), Intersect(), dYdX(), and ddYdX() functions.
Example of the use of Spline(), Interp(), and Interpolate() functions.
KEY BENEFITS
XlXtrFun has been used for years by engineering and research and development personnel in Europe, South America, and North America who need to interpolate, extrapolate, and curve fit data rapidly, reliably, and with a virtually non-existent learning curve. As the Spline() function example above shows, you define your curve in the first two function arguments by giving it some x's and an equal number of y's. The next argument is the x for which you want the interpolated value, and the function returns the y at that x. We can't imagine an easier way to do things.
The functions also allow for overriding the various default methods of the functions by specifying values for the optional arguments.
Most functions also have exported versions for use by Visual Basic for Applications within the Excel Visual Basic programming environment. Exported versions are also available for "pure" Visual Basic, C, C++, FORTRAN, etc.
LIST OF FUNCTIONS
1D Numerical Functions
LookupClosestValue
Returns the element in an array which is closest to a given value
IndexOfClosestValue
Returns the 1-based index of the element in an array which is closest to a given value
2D Numerical Functions
LookupClosestValue2D
Returns the element in a 2-D array which is closest to two given values
Pfit
Returns the Y which lies on the polynomial line fit by the least squares method
PfitData
Returns the coefficients and statistics for the polynomial line fit by the least squares method
Spline
Returns the Y which lies on the cubic (or natural) spline curve at the given X
Interpolate
Returns the Y which lies on an interpolated curve at the given X
Interp
Returns the Y which lies on an interpolated curve at the given X using the defaults of Interpolate
XatY
Returns the X value at the Max. (Peak),. Min (Valley), or Given Y of an interpolated curve
Intersect
Returns the X value at the intersection of two lines defined by arrays of points
ddydx
Returns the second derivative of the interpolated curve at the given X using the defaults of Interpolate
dydx
Returns the first derivative of the interpolated curve at the given X using the defaults of Interpolate
3D Numerical Functions
Interp3D
Returns an interpolated Z for known X's, known Y's, known Z's, and a given X and Y using the defaults of Interpolate
InterpMatrix
Given an X, Y, Z matrix like an efficiency hill curve matrix, interpolates or extrapolates a Z using the defaults of Interpolate
Note: 3-D Interpolation from ordered input data is part of XlXtrFun and is what the previous two functions do. Surface Generation from Scattered Input Data is now released and included in the zip file.
Low Level I/O Functions
InputByte
Inputs a byte from a given I/O port
OutputByte
Outputs a byte to a given I/O port
EXPORTED FUNCTIONS
Most functions also have "exported" versions which can be called from other programs written in Visual Basic, Visual Basic for Applications, C, C++, Fortran, etc.
SYSTEM REQUIREMENTS
Computer:
486DX PC or above.
Memory:
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. To use exported functions only, Microsoft Excel is not required.
INSTALLATION
Click here for installation instructions that will open in a new window. This HTML document is also included in the zip file you download, so you really do not need to look at it at this point in time.
DOWNLOAD NOW - It's free
http://www.xlxtrfun.com/XlXtrFun/XlXtrFun.htm
Copyright © 2002 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.
Other products and companies referred to herein are trademarks or registered trademarks of their respective companies or mark holders.
See also: Index to Excel VBA Code and Index to Excel Freebies and Lesson 1 - Excel Fundamentals and Index to how to… providing a range of solutions and Index to new resources and reference sheets
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Click here to visit our Free 24/7 Excel/VBA Help Forum where there are thousands of posts you can get information from, or you can join the Forum and post your own questions.