Category Archives: General Mathematics

Tree Height Measuring Example

Posted on 10-September-2015 by mathscinotes

I have been testing a number of Android applications that are intended to measure the size of objects knowing their range or vice versa. One application that I have found particularly useful is called Baumhöhenmesser – Tree Height Meter (my translation) – which is an application written by a German developer. I have found this application particularly useful, and I thought I would review its operation here. It is part of a suite of Android applications intended for forestry management. This app makes excellent use of the Android's ability to measure angles. Continue reading →

Posted in General Mathematics, Geometry | 3 Comments

Stadiametric Rangefinding Approaches

Posted on 20-July-2015 by mathscinotes

Recently, I was reading about stadiametric range finding methods being used by hunters and their telescopic sights – I was surprised to find a lot of writing on the topic. As I researched the topic, I saw that there are three common approaches used in telescopic sights: milliradian (mil), Minute Of Angle (MOA), and Inch Of Angle (IOA). I will review these methods here. Continue reading →

Posted in Ballistics, General Mathematics | 2 Comments

Optical SFP Power Estimation Using Curve Fitting

Posted on 26-May-2015 by mathscinotes

I was asked today how to use Excel to estimate the power usage of two optical components at case temperatures for which we had no data. I initially solved the problem in Mathcad by fitting an equation of the form $latex c_0 \cdot e^{c_1 \cdot T_{Case}}+e_2 to the data and computing the corresponding power. Continue reading →

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Negative times a Negative is a Positive

Posted on 12-April-2015 by mathscinotes

On my team, I work hard to ensure that we have a non-threatening environment for questions – any questions. In fact, I often ask very basic questions in meetings so that I can make sure that I understand all the nuances of a situation. You would be amazed how often I learn things from asking questions so basic that you would think asking them would not be necessary. Continue reading →

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Prime Number Magnitudes

Posted on 9-April-2015 by mathscinotes

I am responsible for some of the authentication features in our products and these features use prime numbers. People often have basic questions on prime numbers, such as:

What happens if I choose the same prime number as someone else?
Are there enough prime numbers? Continue reading →

Posted in General Mathematics, software | Comments Off on Prime Number Magnitudes

Donor Chain Math

Posted on 20-January-2015 by mathscinotes

I just read an interesting article at Ars Technica on the mathematics behind setting up donor chains. The math is actually a variant of the prize-collecting traveling salesman problem, which is NP-hard. Continue reading →

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Cat Litter and Radioactivity

Posted on 13-January-2015 by mathscinotes

I am not a cat person – the only time that cats come up in my family is in regards to Schrodinger's cat (Figure 1). However, I just came across an interesting web page by the Oak Ridge Associated Universities that discusses cat litter and the fact that it is slightly radioactive. Some cat litter is slightly radioactive because the contain bentonite clay, which contains small amounts of radioactive uranium (238U), thorium (232U), and potassium (40K). I find this web page interesting because it includes measured radiation data and an estimate of the heavy metals (uranium and thorium) that are contained in cat litter. Continue reading →

Posted in General Mathematics, General Science | 4 Comments

Clever Way of Putting on a Duvet Cover

Posted on 22-December-2014 by mathscinotes

My wife and I put on a Christmas-themed duvet cover last night using the technique shown in this video. The approach reminds me of some topology demonstrations. The method worked as advertised. Continue reading →

Posted in General Mathematics, Geometry | 2 Comments

Mathcad Matrix Example

Posted on 4-December-2014 by mathscinotes

Introduction A friend of mine recently converted his propane-fueled grill to a natural-gas fueled grill and he mentioned to me that he had to get a new pressure regulator and different-sized gas orifice, neither of which I knew anything about. … Continue reading →

Posted in General Mathematics | 4 Comments

Repairing My Electric Dryer and a Little Math

Posted on 10-July-2014 by mathscinotes

I came home the other night and my wife reported that our clothes dryer was not generating any heat for drying clothes. She called a repairman and he could not repair our dryer for a long time and was going to charge a lot of money (e.g. $90 for a heater coil that was $30 from Amazon). While I know NOTHING about clothes dryers, I decided to try to fix it myself. As with most of my repair adventures, I started with Youtube. After a couple of minutes, I found the following video where a repairman gave a great demonstration on how to change the heater coil (Whirlpool part number 3387747) in my clothes dryer. Continue reading →

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