Category Archives: Maths

Plotting Freeze-Thaw Data …

… or other irregular cyclic data. Another Eng-Tips question asked how to approximate ice area over a freeze-thaw cycle using a function based on a sine or cosine curve.  The screen-shot below shows three alternatives: Using built in Excel functions requires … Continue reading

Posted in Arrays, Curve fitting, Excel, Maths, Newton, UDFs, VBA | Tagged , , , , , | 1 Comment

Counting non-pecked chicks

Download file:  Binary Chicks.zip. This post is based on a recent discussion at Cosmic Horizons looking at numerical methods to solve the following problem: The answer to the question is straightforward: With a little thought, you should be able to realise … Continue reading

Posted in Excel, Link to Python, Maths, Newton, UDFs, VBA, xlwings | 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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Weighted Least Squares Regression, using Excel, VBA, Alglib and Python

Least squares linear regression in Excel is easy.  That’s what the Linest and Trend functions do.  That is, they find the coefficients of a straight line (or higher dimension shape) so that the sum of the squares of the distances of … Continue reading

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

On the probability of frog croaks.

A recent logical puzzle from TED discussed the probability of one of two frogs being female, if we know that at least one of them is male: This puzzle is discussed (arriving at different conclusions) here: and puzzles of this … Continue reading

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Brent’s Method and a daft engineer’s blog

Browsing links on Brent’s Method I found: Daft Engineer – Numerical Methods and Excel* which is well worth a look (plenty of stuff on statistics and Python, with the odd dash of Excel).  The link has VBA code for a … Continue reading

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