Monthly Archives: May 2019

Using Excel to Convert a Number List to Dashed String of Ranges

Posted on 18-May-2019 by mathscinotes

While working on a test report for an aircraft manufacturer this week, I needed to convert a large number of number lists to strings of dashed ranges. For example, suppose you are given a list {1, 2, 3, 5, 6, 7, 8, 10}. Converting this list to a dashed set of ranges means generating the string "1-3, 5, 6-8, 10." Figure 1 shows another example with an optional prefix added to each number. Continue reading →

Posted in Excel | 1 Comment

US Iron and Aluminum Mining During WW2

Posted on 4-May-2019 by mathscinotes

My vacation/retirement cabin is in the iron mining region of Minnesota. The rock throughout the area shows the reddish hue of iron. I recently heard some old-timers talking about how the intensity of mining operations during WW2 took the last of the high-grade iron ore (hematite –Figure 1) and left only low-grade ore (taconite). This comment made me curious about mining during WW2. Continue reading →

Posted in History Through Spreadsheets | 6 Comments

Estimating Exponential Time Constants

Posted on 2-May-2019 by mathscinotes

I have been presented with a large amount of experimental data from which I need to determine many exponential time constants. There are so many time constants to calculate that I need to automate the process. Continue reading →

Posted in General Mathematics | Comments Off on Estimating Exponential Time Constants