Are slide rules still useful?
johndcook.com
johndcook.com
Even glider pilots use them to calculate best-speed-to-fly (between thermals): http://www.126association.org/glideslide.htm It takes a cool head to: navigate, aviate and run the slide rule accurately all the while remaining aloft without an engine and merely a glide ratio of 12:1!
This was the late 80s, and I couldn't find one. So, I found plans for one in the public library and built one. Later a math teacher gave me his.
Playing with slide rules would be useful. Building a slide rule would be even more useful.
Calculators are obsolete
and then
as far as software for serious math, I use a combination of Python, Mathematica, C++, and C#. For quick calculations I’d use Python. For simulations I’d use C++ for maximum speed or C# if I need to interface with .NET software. I mostly use Mathematica for symbolic computations and plotting.
Kind of an idiosyncratic justification for the obsolescence of calculators. Besides if you think a slide rule gives a good intuition for logarithms, pushing function buttons (e.g., square root) repeatedly on a calculator provides insight into limits.
Always thought I should buy a slide rule and learn to use it so if I'm still around when civilization falls... (I know some might argue that event has already happened.)
There's little reason for a non-student to use one. You'd be paying more for less capabilities, because what you're really paying for is the trust that schools put in its lack of capabilities.
Then again, by the time one is done translating an algorithm into TI speak, one's understanding is as high or higher than a student who spent that time learning to execute the algorithm by hand...
The problem with using slide rules as a replacement is that students would complain too much about learning something they won't ever use to ever get the deeper understanding that Cook talks about. Most young people who don't want a career in math, science, engineering, etc do not want a deep understanding of the principles - they want an A on the test. Unless you can use one of the external tools as a shortcut they won't be willing to put the effort into learning from it rather than using it.
Ban calculators, ban slide rules, ban everything except pencil and paper and hope that people gain some smidgen of understanding through sheer force of not having any other option.
Perhaps students could expand a series to approximate a log etc. Again, why? Spends a lot of time that could be spent moving forward in math.
Slide rules are primarily visual and manipulated non-digitally. Using one is quite relaxing. The calculator interface demands "numbers as a sequence of digits" and you must type each digit and operation. But with a slide rule, numbers are values (usually 3-digit) on a number line instead. The analog nature of the computation fits the human brain well IMO.
My favorite was a circular slide rule since it eliminated multiplications (logarithmic additions) that were off the scale (which on most slide rules mandated a shift of the slide to the opposite side).
One of the initial attractions of electronic calculator when they first became commonly available was the increased number of significant digits, yet it is amazing how much was done previously using only three.
Sure, some are going to computers for the math, but laminated paper holds up better under extreme conditions for almost free.
In all seriousness, I don't know how to use it, but I should learn. It could come in handy when/where power isn't available. It's amazing how much our knowledge would decline in the event computers & electronic gadgets were somehow destroyed or unusable. I've always tried to learn the basics. For example, when out hiking, I use a map, compass, and protractor -- and use my GPS as a backup.
Anyone have any useful links for non-mathematicians learning to use one?
http://sliderulemuseum.com/SR_Course.htm
http://www.sliderule.ca/intro.htm
http://www.sphere.bc.ca/test/howto.html
http://www.hpmuseum.org/srinst.htm
http://thinkgeek.com/files/slide_rule_manual.pdf
I am relearning how to use a slide rule (I'm old enough that I had lessons in using a slide rule in my secondary education) to teach basic principles to the pupils in my advanced supplementary mathematics course this summer.
Granted, spreadsheets do all of that and more, but it can sometimes be quicker to punch it all into a calculator, especially if you're already using one.
I have my grandfather's sliderule as a keepsake, and got fairly decent at using it a few years back. I've fallen out of practice now, so if I wanted to produce a series of numbers it'd be quicker for me to write a little python program than try to remember how to use the sliderule.
On the subject of graphing calculators, saying that you don't need a $100 graphing calculator because you can buy a $200 netbook is as silly as trying to compare an e-reader to a netbook.
On the other hand, there's no reason a good e-reader couldn't also be a good graphing calculator. And the pricing is similar.
Indian Chief SOHCATOA:
S=O/H C=A/H T=O/A
where S, C, T, O, A, H are respectively, sin, cos, tangent, opposite, adjacent, and hypotenuse. The mnemonic stuck immediately.
Surprised, I asked if all the formulae in the 3-inch text were in terms of those formulae, to which she replied affirmatively. I immediately realized there was little need to study trig whatsoever, since any of the complex formulas could be reduced to ratios using the SOCAHTOA principle. I barely cracked the text that semester. She disapproved somewhat of my methods but accepted them. My classmates wasted hours memorizing formulas.