Category Archives: Maths

Numerical integration with on-sheet calculations

Posted on 08/07/2020 by dougaj4

Following a comment here I have prepared a spreadsheet that works through the Tanh-Sinh Quadrature process with on-sheet calculations.  For that purpose Graeme Dennes has provided a simplified version of the code: QUAD_RODRIGUEZ_TANH_SINH for finite intervals. Translated from HP RPN … Continue reading →

Posted in Excel, Maths, Newton, Numerical integration, UDFs, VBA | Tagged , , , , , | 10 Comments

LinEstGap with non-linear functions

Posted on 14/03/2020 by dougaj4

The LinEstGap user defined function (UDF) allows the built-in Linest function to be used on data with empty cells or hidden rows, returning results that agree with the chart trend-line function, which automatically ignores blank cells and hidden data.  It … Continue reading →

Posted in Arrays, Curve fitting, Excel, Maths, Newton, UDFs, VBA | Tagged , , , , , , , , , | 4 Comments

Katherine Johnson, NASA Legend

Posted on 26/02/2020 by dougaj4

Cartoon by Steve Breen from The San-Diego Union Tribune. More on Katherine Johnson.

Posted in Maths, Newton | Tagged , , | Leave a comment

Asymmetric Catenary Function

Posted on 31/01/2020 by dougaj4

Back in 2009, I posted a user defined function (UDF) to generate a catenary curve, that could be used together with the Excel Solver to generate a curve of a specified span and sag: A catenary function Following a discussion … Continue reading →

Posted in Coordinate Geometry, Curve fitting, Excel, Maths, Newton, UDFs, xlwings | Tagged , , , , | 1 Comment

More powers of 3

Posted on 20/10/2019 by dougaj4

Following the discovery of a question to which the answer is 42, the same team has now reported a sum of three cubes equal to 3.  As before, the result can be checked from Excel, linking to mpmath, via pyxll. … Continue reading →

Posted in Computing - general, Excel, Link to Python, Maths, Newton, PyXLL | Tagged , , , , , | Leave a comment