Category Archives: Maths

Update to AL-Spline-Matrix

Posted on 28/11/2017 by dougaj4

The AL-Spline-Matrix spreadsheet contains a large number of VBA user defined functions (UDFs) performing spline fitting and matrix operations, using the free and open source ALGLIB library. It was recently pointed out that the Excel interface code for the CSplineFitCW1da … Continue reading →

Posted in AlgLib, Excel, Maths, Newton, UDFs, VBA | Tagged , , , , , , | 1 Comment

Hofstadter, Pahud, Bach

Posted on 08/10/2017 by dougaj4

The latest ACO concert series features the Swiss flautist Emmanuel Pahud (interview here). The performance included J.S. Bach’s 6 Part Ricercar, from The Musical Offering, which was the inspiration for the final dialogue in Douglas Hofstadter’s Godel, Esher, Bach: Achilles … Continue reading →

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Working with implied units – update

Posted on 30/09/2017 by dougaj4

Following comments at Eng-Tips I have added two examples with different procedures for evaluating ACI equations for the flexural tensile strength of concrete here.

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Using Alglib least-squares solvers

Posted on 23/09/2017 by dougaj4

Following the last post on using the Python version of Alglib from Excel, via xlwings, this post looks in more detail at alternatives for fitting a non-linear function to a set of data, using the Levenberg-Marquardt method.  The spreadsheet with … Continue reading →

Posted in AlgLib, Curve fitting, Excel, Link to Python, Maths, Newton, NumPy and SciPy, UDFs, VBA, xlwings | Tagged , , , , , , , , , , | 2 Comments

Working with implied units

Posted on 19/09/2017 by dougaj4

The Units4Excel spreadsheet provides a number of functions to convert between different units and evaluate functions entered as text on the spreadsheet, taking account of the units of both the inputs and the results.  The latest version can be downloaded from: … Continue reading →

Posted in Concrete, Excel, Maths, Newton, UDFs, VBA | Tagged , , , , , , , , , , , , | 2 Comments