Digital Slide Rule

The Animated Software Company

Contains ads

About this app

The slide rule was used for over 400 years as a calculating/estimation tool. Abandoned with the advent of hand-held calculators, computers and smart phones, their elegant simplicity is still a thing of wonderment. This program replicates the most common types of slide rules: Straight, circular, spiral and cylindrical. Dozens of scales are included and numerous features that could never exist on a physical slide rule are also included, such as color options, numeric displays of the values under the hairlines, and so on.

Slide rules were used to go to the moon and to build bridges, skyscrapers, tunnels, aqueducts and nearly everything else. Slide rules were simple to use and accurate enough for most occasions.

Please note that this program is processor-intensive and with heavy use, will probably drain your battery fairly quickly. Every effort has been made to make the program efficient, but nevertheless, some functions take a few moments to occur, including initial load, which can take three or four seconds, or perhaps a little longer. Nearly 30,000 "nibs" are created during this time, as well as over 3,000 labels, so please be a little patient!

Because of all the detail, it looks best and runs best on a large-format machine such as a tablet. Also because of all the detail, the 30-loop spiral slide rule converts to a low-rez "bitmap data image" while you move it, then back to a "vector based image" as soon as you release.

Includes a brief side show slide show of famous and interesting slide rules, most of which are in the author's collection. Two are public-domain photographs of antique slide rules.

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Notes on usage: Program features include "two-finger pinch/zoom." Slide rule slide show images can also be rotated. Enlarge an image by double-tapping in the same place. Tapping three times in the same place will return the program to the home position. Tapping four times will bring up an intro-screen message which requires tapping anywhere to remove.

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This program was first released in 2016 and is the product of a lifelong love of numbers (and 30+ years of programming experience!).

Special thanks to the Oughtred Society for their member's invaluable help in evaluating the earliest versions of this program.

Ratings and reviews

Every slide rule is animated. App can be moved to external SD memory. It even includes the rather rare "P" and "Q" scales, which solves for the Pythagorean theorem: Let P = 3, and Q = 4. Then P x Q = 5. With android smart phone models introduced after Jan 1, 2020, the sluggishness problem, related to computing new values, is now non-existent. I would gladly pay a fee to remove the ads.

Slide rules are still handy for getting a quick and dirty estimate of the answer to a complicated problem. This app, however, doesn't give that experience. It's cumbersome to use, zooming is not ideal for this use case. The circular slide rule works well due to limited screen space and should probably be the default, but the controls are still tricky to master.

I should say that this app is a nicely animated historical lesson on how to estimate multiplication & division using rulers. It's very interesting though if I want to fiddle around more easily, I should but a slide rule by myself and learn from its manual book. Why? Because of the sensitivity of the screen, it's hard for me to align the small lines.

What’s new

Faster setup time after program is loaded (as much as 50% faster); streamlined internal processing (especially of Cylindrical Slide Rule); corrected "Display Estimated Hairline Values" for several of the alternate scales.