Tag Archives: curve fitting

Excel to Alglib via xlwings

The Alglib library provides many valuable numerical analysis routines, but the VBA version is no longer actively maintained.  The latest versions are available in C++, C#, and Python, of which the Python version (in conjunction with xlwings) provides the easiest interface … Continue reading

Posted in AlgLib, Curve fitting, Excel, Link to Python, Maths, Newton, Numerical integration, UDFs, VBA, xlwings | Tagged , , , , , , , , , | 3 Comments

ExcelPython2, Alglib and Spline-Matrix update

The ExcelPython add-in, offering easy access to Python code from Excel VBA, has had a major update to Release 2.  The new version provides new features and simpler installation, but has some incompatibilities with code written for the previous  version, so the … Continue reading

Posted in AlgLib, Excel, Link to Python, Maths, Newton, UDFs, VBA | Tagged , , , , , , , , | 4 Comments

Daily Download 22: Splines and Curves

Since it was first published in 2009 my CSpline function has been the most popular download from this site.  CSpline (and various associated functions) is used to fit a series of cubic curves through specified points, allowing interpolation along a smooth … Continue reading

Posted in AlgLib, Beam Bending, Charts, Charts, Coordinate Geometry, Excel, Newton, Numerical integration, UDFs, VBA | Tagged , , , , , , , , | 6 Comments

Spline Interpolation Alternatives

A recent post at Jon Peltier’s Blog looks at an “on-sheet” method of performing linear interpolation on a set of tabular data, and the following comments include a number of alternative ways of carrying out the same process, and also some … Continue reading

Posted in Excel, Maths, Newton, UDFs, VBA | Tagged , , , , , | 7 Comments

Fitting high order polynomials

This post is a follow up to Using LINEST for non-linear curve fitting and the following comments from Scott Rogers and Lori Miller.  Scott found that he was getting different results from Linest and the xy chart trend line for polynomials of … Continue reading

Posted in AlgLib, Charts, Excel, Maths, Newton, UDFs, VBA | Tagged , , , , , , , , | 27 Comments

Using LINEST for non-linear curve fitting

Update 28 June 2015:  Also see Using Linest for non-linear curve fitting examples, hints, and warnings for more examples of fitting exponential and polynomial curves using LinEst. A frequent question on internet forums everywhere is how to do a least squares fit … Continue reading

Posted in Charts, Excel, Maths, Newton | Tagged , , , , , | 90 Comments