Author Archives: dougaj4

LinEstGap with non-linear functions

Posted on March 14, 2020

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 , , , , , , , , , | 1 Comment

DigitGraph Spreadsheet and WebPlot Digitiser

Posted on March 3, 2020

I have posted here previously a spreadsheet that allows XY data to be extracted from images of graphs, maps or other images of objects in a single plane: How to digitise a scanned image. I have updated the instructions for the … Continue reading →

Posted in Charts, Charts, Computing - general, Curve fitting, Drawing, Excel, UDFs, VBA | Tagged , , , , , | 5 Comments

Katherine Johnson, NASA Legend

Posted on February 26, 2020

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

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

Microsoft Python Resources

Posted on February 24, 2020

In addition to the documentation of their software products, Microsoft now have a huge amount of on-line resources of more general content, including: YouTube: Python for Beginners Probably the largest hurdle when learning any new programming language is simply knowing … Continue reading →

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

Paul Kelly and Joni Mitchell

Posted on February 8, 2020

Leading Australian singer-songwriter Paul Kelly is about to release a powerful new single that tackles Australia’s lack of action on climate change and environmental destruction. Entitled Sleep, Australia, Sleep, Kelly says the song is both “a lament in the form … Continue reading →

Posted in Bach, Climate | Tagged , , , | Leave a comment

Asymmetric Catenary Function

Posted on January 31, 2020

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 , , , , | Leave a comment

Using Excel Solver from VBA

Posted on January 28, 2020

Using the “record macro” icon in Excel to record the solver process, I had a couple of problems: When I tried to run the recorded macro, I got the message “Compile Error – Sub or Function not defined”. When that … Continue reading →

Posted in Excel, VBA | Tagged , , , , | 1 Comment