Author Archives: dougaj4

Solving cubic equations – background and timing

For more information on the polynomial functions, including quartic and higher order solvers, see: Solving Quadratic, Cubic, Quartic and higher order equations; examples Re-reading the Wikipedia article on solving cubic equations, I noticed that the trigonometrical solution for finding 3 real … Continue reading

Posted in Excel, Link to Python, Maths, Newton, NumPy and SciPy, PyXLL, UDFs, VBA | Tagged , , , , , , , , , | Leave a comment

Working with Python polynomials from Excel

Python polynomial functions have several features that require manipulation of data passed from Excel: I have written 3 short Python functions to deal with passing arrays of complex numbers from and to Excel, using pyxll, or within Python code to … Continue reading

Posted in Arrays, Excel, Link to Python, PyXLL, UDFs | Tagged , , , , , , , , , | Leave a comment

A Match Function Bug …

… or at least, a non-intuitive feature of the MATCH function, that may give inconsistent results. This post is based on a discussion at EngTips. The problem under discussion was to find the number of the first and last rows … Continue reading

Posted in Arrays, Excel | Tagged , , , | 3 Comments

3D plots with the latest Matplotlib

Installing Python on a new computer, I found I had to downgrade Matplotlib to release 3.5.2 to get my 3D plotting functions to work. Further investigation found that the problem was the Axes3D function. Changing:     ax = axes3d.Axes3D(fig)to: … Continue reading

Posted in Animation, Coordinate Geometry, Drawing, Excel, Link to Python, Newton, NumPy and SciPy, PyXLL, UDFs | Tagged , , , , , , | 2 Comments

Installing Python and pyxll from scratch

Updated 28th September 2022. Matplotlib latest version OK. I recently installed Python and pyxll (plus the required additional libraries) on a new computer, which raised a few problems with incompatible versions, so here is a summary of what worked (as … Continue reading

Posted in Animation, Arrays, Charts, Coordinate Geometry, Differential Equations, Excel, Finite Element Analysis, Link to Python, Maths, Newton, Numerical integration, NumPy and SciPy, Python Pandas, PyXLL, UDFs | Tagged , , , , , , , , , , , , , , | Leave a comment