Author Archives: dougaj4

Elegant proofs – more Pythagoras

Posted on 01/03/2018 by dougaj4

Browsing the Plus Magazine site recently, I was struck the proof of Pythagoras’ Theorem shown in the animation below: Not just because it is an elegant proof, but also because of the author, the 20th President of the United States, … Continue reading →

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

More Python rotation functions

Posted on 23/02/2018 by dougaj4

The code described in the previous post includes a Python function that rotates 3D coordinates by an angle defined with two vectors, using Rodrigue’s Rotation.  I have now added this function to the IP2_py spreadsheet, where it is used in the … Continue reading →

Posted in Coordinate Geometry, Drawing, Excel, Link to Python, Maths, Newton, NumPy and SciPy, UDFs, VBA, xlwings | Tagged , , , , , , , , | Leave a comment

Fitting 3D circles to scattered points

Posted on 11/02/2018 by dougaj4

Following a comment at update-to-glob_to_loc3-and-loc_to_glob3-functions, I have modified the Python code at the linked site, so it can be run from Excel, via xlwings.  The spreadsheet described below, and the associated Python code, can be download from: 3DCirc.zip The original … Continue reading →

Posted in Coordinate Geometry, Excel, Link to Python, Maths, Newton, NumPy and SciPy, UDFs, VBA, xlwings | Tagged , , , , , , , | 7 Comments

Cubic splines with jagged data

Posted on 07/02/2018 by dougaj4

A cubic spline provides a good approximation to a smooth curve, and alternative versions are available for free download (see Daily Download 22: Splines and Curves, Update to AL-Spline-Matrix, and xlwSciPy 1.09 – update for xlwings 0.10 and Scipy 0.18.1), but if … Continue reading →

Posted in Arrays, Beam Bending, Concrete, Curve fitting, Excel, Newton, UDFs, VBA | Tagged , , , , , , | 2 Comments

More on building bridges, not walls

Posted on 03/02/2018 by dougaj4

In June last year I posted a link to a Jeremy Corbyn speech on the topic of building bridges, not walls. Here are a couple of (more poetic) links on the same topic. The first is from Anaïs Mitchell.  This … Continue reading →

Posted in Bach | Tagged , , | 1 Comment