Category Archives: Drawing

DigitGraph Spreadsheet and WebPlot Digitiser

Posted on March 3, 2020 by dougaj4

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 dougaj4

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 dougaj4

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 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

Use Matplotlib from Excel with xlwings

Posted on February 14, 2016 by dougaj4

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