Category Archives: Drawing

DigitGraph Spreadsheet and WebPlot Digitiser

Posted on March 3, 2020 by

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

Plotting Mandelbrot

Posted on September 15, 2019 by

There are many sites discussing the Mandelbrot Set, but not many examples using VBA to plot the set in Excel, so here is my effort: The spreadsheet (including open source VBA code) may be downloaded from: Mandelbrot chart.zip Note that … Continue reading →

Posted in Charts, Charts, Coordinate Geometry, Drawing, Excel, Maths, Newton, VBA | Tagged , , , | 3 Comments

Arcs and arc-splines

Posted on August 17, 2018 by

I have added two user defined functions (UDFs) to the IP2 spreadsheet to generate coordinates for a single  arc, or a series of arcs connected (if necessary) by straight lines.  The new version may be downloaded from: IP2.zip As an example … Continue reading →

Posted in Animation, Charts, Charts, Coordinate Geometry, Drawing, Excel, Maths, UDFs, VBA | Tagged , , , , , , | 1 Comment

More Python rotation functions

Posted on February 23, 2018 by

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

Use Matplotlib from Excel with xlwings

Posted on February 14, 2016 by

Xlwings is another free and open source package allowing communication between Excel and Python.  It now incorporates ExcelPython, and is included in the Anaconda Python package, so will support my ExcelPython based spreadsheets after installation of xlwings using: conda install … Continue reading →

Posted in Drawing, Excel, Link to Python, Maths, Newton, Numerical integration, NumPy and SciPy, VBA | Tagged , , , , , , | 8 Comments

Section Properties – Lunes and Groups

Posted on July 8, 2015 by

Following a discussion at Eng-Tips and resulting comments I have updated my Section Properties spreadsheet to include calculation of the area and centroid of a “Lune” (the shape of a crescent moon).  I have also added a “Re-draw Shape” button because … Continue reading →

Posted in Drawing, Excel, Maths, Newton, VBA | Tagged , , , , | 2 Comments

“Yields circularity when preceded by its quotation” …

Posted on April 15, 2014 by

yields circularity when preceded by its quotation. Today’s post takes us on a little circular tour of the internet, starting with: Grumpy Old Programmer (Mike Woodhouse) who returns from a long holiday from blogging to publish a nice little routine … Continue reading →

Posted in Computing - general, Drawing, Newton | Tagged , , , , , | Leave a comment