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Category Archives: Charts
DigitGraph Spreadsheet and WebPlot Digitiser
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 DigitGraph, digitize scanned image, Excel, UDF, VBA, WebPlot Digitizer
5 Comments
Plotting Mandelbrot
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 Charts, Excel, Mandelbrot Set, VBA
3 Comments
Iterative solvers and arrays
A recent thread at Eng-Tips was looking for a solution to the problem described below: The solutions to this problem described below can be downloaded from: ItSolve.zip and xlScipy3.zip The ItSolve.xlsb spreadsheet contains a user defined function (UDF) to solve iterative … Continue reading
Posted in Arrays, Charts, Excel, Link to Python, Maths, Newton, NumPy and SciPy, UDFs, VBA, xlwings
Tagged Brents method, Excel, Python, SciPy, UDFs, VBA, xlwings, xlwSciPy3
2 Comments
Arcs and arc-splines
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
Plotting Charts With Gaps …
“How do you get VB6 to initialize doubles with +infinity, -infinity and NaN”… and various sorts of Not a Number. Back in 2012 (When is an xy chart not an xy chart) I concluded that it was not possible to … Continue reading
Posted in Arrays, Charts, Charts, Excel, UDFs, VBA
Tagged Chart, NaN, plot blank, XY chart with gaps
5 Comments
Using Matplotlib from Excel with xlwings – update
In February 2016 I posted a spreadsheet with examples of linking to the Python Matplotlib library with xlwings. Since then updates to xlwings required some changes to the python code, specifically plot.show has been replaced with pictures.add. The spreadsheet has … Continue reading
Posted in Charts, Charts, Excel, Link to Python, Newton, NumPy and SciPy, VBA
Tagged Excel, MatPlotlib, Python, update, VBA, xlMatPlot, xlwings, xlwScipy
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More on trend line equations on line charts
In the previous post we saw that if a trend line equation is added to a line chart it will return the wrong coefficients if the x values are not a continuous sequence of integers, starting at 1 (click on … Continue reading
Posted in Charts, Excel, Maths, Newton
Tagged chart trend line, Charts, Excel, line chart, XY chart
1 Comment
