Category Archives: Charts

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 , , , , , , , | 1 Comment

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

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

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 , , , | 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 , , , , , , , | Leave a comment

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 , , , , | 1 Comment

Displaying trend line equations on line charts

This post is prompted by a recent comment at Using LINEST for non-linear curve fitting which found that the trend line formula displayed on a chart was totally different from that found using the Linest function. The problem was caused by using a … Continue reading

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A mystery curve links to Jupyter

Reviewing some of my less visited links recently, I was intrigued by a post at The Math Less Travelled: The previous post at the site provides more details of the source of the curve, and some links to an interactive … Continue reading

Posted in Charts, Charts, Excel, Maths, Newton | Tagged , , , , , , | 2 Comments