4 ms·

Are slide rules still useful?

39 points by gnosis 16y ago

lukeschlather 16y ago
I like the suggestion that we use slide rules in elementary. 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.
wazoox 16y ago
Interesting idea. As a side note, I'm 40 and I've seen an actual slide rule exactly once, a few years ago, and I haven't got the slightest idea on how to operate one.
ajdecon 16y ago
I actually played with a slide rule quite a bit when I was in middle school (but not in school), and it was much more useful as an actual learning aid than my calculator. The visualization of logarithms is in fact rather helpful.
mhb 16y ago
Obviously not the main point, but he says 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.
- gaius 16y ago
  They are not tho'. It's about the user interface. I have a PC here with 2 big screens, I have access to a compiler/REPL for any language you can name (or at least, that I can apt-get) and I still use a calculator, because a purpose-built interface will always trump a generic one for a specific task. It's why cars have steering wheels still and not QWERTY keyboards. The only thing the calculator doesn't do is c'n'p into another window.
ericmoritz 16y ago
I think learning sin/cos/tan before learning that they are based on a circle is ridiculous as well. I had an epiphany when I learned that.
- giardini 16y ago
  After concluding plane geometry we took trigonometry. The teacher had chosen an ugly pink-and-black text from New York State. No less than 3 inches thick, it was chock full of trigonometric formulae for us to memorize. But on day 1 she put the following on the blackboard: 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.
  - gjm11 16y ago
    I've no idea what was in your ugly pink and black textbook, but I'd have thought those trigonometric formulae would include lots of things like cos(A+B) = cos(A)cos(B) - sin(A)sin(B). How do you "reduce that to a ratio using the SOHCAHTOA principle"? By drawing a diagram with two right-angled triangles stuck together and doing the relevant fiddly geometry? That seems like vastly more trouble than remembering the formula. (It took me a minute to work out how to derive the formula at all that way, and I'm a pro.)
keithba 16y ago
As a kid I was an avid reader of Heinlein and Asimov, and they were always talking about slide rules (Astrogators navigated space with them!) 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.
- root 16y ago
  The following cover from Astounding springs to mind: http://up-ship.com/blog/wp-content/uploads/2010/04/feb59a.jpg http://up-ship.com/blog/wp-content/uploads/2010/04/feb59a.jp...
hsmyers 16y ago
I'd suggest that on the same lines, a class in ancient computers might be a way to spark the imagination. Napier's Bones, Pascal's Adding machine, Babbage's Difference engine and the like. They did it for me when I first learned about them and still do--- how about the hand-held navigational device found in the Greek harbor! Lots of things to add to the list along with the venerable slide rule.
rfreytag 16y ago
Pilots use slide rules. Behold the venerable E6B flight computer (aka "Whiz Wheel"): https://secure.wikimedia.org/wikipedia/en/wiki/E6B https://secure.wikimedia.org/wikipedia/en/wiki/E6B Even glider pilots use them to calculate best-speed-to-fly (between thermals): http://www.126association.org/glideslide.htm 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!
- artmageddon 16y ago
  Pilot here(private pilot, anyway), and yes: we use the E6B a lot when we're up there. It's nice that avionics can give us things like true airspeed and fuel burn rate instantaneously, but that's only as good as your power source is when it's working correctly. An E6B will never suffer from electrical failure.
  - fractallyte 16y ago
    But it might suffer from illumination failure!
    - artmageddon 16y ago
      That's why we carry flashlights :)
- bergie 16y ago
  I also confess to trusting these whiz wheels ("kakkara", we call them in Finnish), a clock, and my thumb on a map way more than I do trust GPSs and glass cockpits.
camiller 16y ago
Online slide rule: http://www.engcom.net/index.php?option=com_sliderule&Itemid=73 http://www.engcom.net/index.php?option=com_sliderule&Ite... 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.)
showerst 16y ago
If anyone wants one, think geek sells them now for $20 US: http://www.thinkgeek.com/interests/gamer/be12/ http://www.thinkgeek.com/interests/gamer/be12/
- tzs 16y ago
  I bought a couple of those out of nostalgia. They aren't very good. The movement is rough, making them kind of annoying to use.
  - ajdecon 16y ago
    Agreed. Sphere sells vintage rules though: http://www.sphere.bc.ca/test/sliderule.html http://www.sphere.bc.ca/test/sliderule.html
- deleted 16y ago
  [deleted]
javanix 16y ago
Despite being cursed with an endless string of horrible (for me - I'm sure some students did well) math classes from high school through college, the one thing I came away from with them was an appreciation of how much more intuitively you can learn mathematics if you don't use a calculator. 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.
- JoeAltmaier 16y ago
  ...and how would you recommend doing logarithms? Thru a table? Why? You would learn approximation techniques, sure, but that teaches you nothing about logarithms, it just spends your time. 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.
jcl 16y ago
The reason that students are required to purchase graphing calculators is for tests, not learning; schools believe they have more control over what goes on during a test if all the students are using the same brand of (locked-down) graphing calculator. 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.
- samatman 16y ago
  And of course, as every aspiring hacker in high school knows, graphing calculators come with a Turing Complete scripting language that's powerful enough to defeat this stricture for most use cases. 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...
runjake 16y ago
I have a Dietzgen No. 1757. It's useful for raising my Apple external keyboard up to be level with my ergonomic wrist pad. 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?
- tokenadult 16y ago
  Anyone have any useful links for non-mathematicians learning to use one? http://sliderulemuseum.com/SR_Course.htm http://sliderulemuseum.com/SR_Course.htm http://www.sliderule.ca/intro.htm http://www.sliderule.ca/intro.htm http://www.sphere.bc.ca/test/howto.html http://www.sphere.bc.ca/test/howto.html http://www.hpmuseum.org/srinst.htm http://www.hpmuseum.org/srinst.htm http://thinkgeek.com/files/slide_rule_manual.pdf 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. http://www.ecae.net/2011/02/summer-2011-course-schedule/ http://www.ecae.net/2011/02/summer-2011-course-schedule/
  - runjake 16y ago
    Thank you for taking the time to post all of these!
maguro 16y ago
What the hell is this crap doing on Hacker News?!?!?!
jordanb 16y ago
Sliderules can be useful, if you're proficient, for performing repeated calculations where only one variable changes. You can slide the indicator along and produce a series of numbers quickly and easily. 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.
giardini 16y ago
Slide rules enhance understanding of the functions used (mostly logarithm & trig) and require keeping mental track of orders of magnitude(so they help avoid _big_ mistakes in quick calculations). 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.
thinkingeric 16y ago
I use a slide rule regularly. It is neither quick nor accurate, but it is useful in the same way that making approximate calculations in your head is useful. That is to say, added precision doesn't help you understand the relationships in a problem and speed can obscure some of what's interesting. However, this kind of thing is only entertaining and instructive for curious people.
ctdonath 16y ago
Snipers use slide rules. The Mildot Master is popular for computing bullet drop from estimated target size and crosshair grid marks. Sure, some are going to computers for the math, but laminated paper holds up better under extreme conditions for almost free.
vault_ 16y ago
One thing that graphing calculators are really useful for is simple number crunching. In academic settings you frequently need to take down numbers and then compute statistics about them. Tables and matrices are probably the 2 most useful things you can do with a graphing calculator (they're also among the least well known, at least among students). 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.
cafard 16y ago
We probably have two around the house: mine from high school chemistry, one that my wife thinks of as a "proportion wheel" from her days in print production. The proportion wheels were in use with printers and publishers for some years after the nerds had gone to calculators.

39 points by gnosis 16y ago

I like the suggestion that we use slide rules in elementary. 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.

wazoox 16y ago

Interesting idea. As a side note, I'm 40 and I've seen an actual slide rule exactly once, a few years ago, and I haven't got the slightest idea on how to operate one.

ajdecon 16y ago

I actually played with a slide rule quite a bit when I was in middle school (but not in school), and it was much more useful as an actual learning aid than my calculator. The visualization of logarithms is in fact rather helpful.

mhb 16y ago

Obviously not the main point, but he says 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.

gaius 16y ago
They are not tho'. It's about the user interface. I have a PC here with 2 big screens, I have access to a compiler/REPL for any language you can name (or at least, that I can apt-get) and I still use a calculator, because a purpose-built interface will always trump a generic one for a specific task. It's why cars have steering wheels still and not QWERTY keyboards. The only thing the calculator doesn't do is c'n'p into another window.

ericmoritz 16y ago

I think learning sin/cos/tan before learning that they are based on a circle is ridiculous as well. I had an epiphany when I learned that.

giardini 16y ago
After concluding plane geometry we took trigonometry. The teacher had chosen an ugly pink-and-black text from New York State. No less than 3 inches thick, it was chock full of trigonometric formulae for us to memorize. But on day 1 she put the following on the blackboard: 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.
- gjm11 16y ago
  I've no idea what was in your ugly pink and black textbook, but I'd have thought those trigonometric formulae would include lots of things like cos(A+B) = cos(A)cos(B) - sin(A)sin(B). How do you "reduce that to a ratio using the SOHCAHTOA principle"? By drawing a diagram with two right-angled triangles stuck together and doing the relevant fiddly geometry? That seems like vastly more trouble than remembering the formula. (It took me a minute to work out how to derive the formula at all that way, and I'm a pro.)

keithba 16y ago

As a kid I was an avid reader of Heinlein and Asimov, and they were always talking about slide rules (Astrogators navigated space with them!) 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.

root 16y ago
The following cover from Astounding springs to mind: http://up-ship.com/blog/wp-content/uploads/2010/04/feb59a.jpg http://up-ship.com/blog/wp-content/uploads/2010/04/feb59a.jp...

hsmyers 16y ago

I'd suggest that on the same lines, a class in ancient computers might be a way to spark the imagination. Napier's Bones, Pascal's Adding machine, Babbage's Difference engine and the like. They did it for me when I first learned about them and still do--- how about the hand-held navigational device found in the Greek harbor! Lots of things to add to the list along with the venerable slide rule.

rfreytag 16y ago

Pilots use slide rules. Behold the venerable E6B flight computer (aka "Whiz Wheel"): https://secure.wikimedia.org/wikipedia/en/wiki/E6B https://secure.wikimedia.org/wikipedia/en/wiki/E6B Even glider pilots use them to calculate best-speed-to-fly (between thermals): http://www.126association.org/glideslide.htm 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!

artmageddon 16y ago
Pilot here(private pilot, anyway), and yes: we use the E6B a lot when we're up there. It's nice that avionics can give us things like true airspeed and fuel burn rate instantaneously, but that's only as good as your power source is when it's working correctly. An E6B will never suffer from electrical failure.
- fractallyte 16y ago
  But it might suffer from illumination failure!
  - artmageddon 16y ago
    That's why we carry flashlights :)
bergie 16y ago
I also confess to trusting these whiz wheels ("kakkara", we call them in Finnish), a clock, and my thumb on a map way more than I do trust GPSs and glass cockpits.

camiller 16y ago

Online slide rule: http://www.engcom.net/index.php?option=com_sliderule&Itemid=73 http://www.engcom.net/index.php?option=com_sliderule&Ite... 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.)

showerst 16y ago

If anyone wants one, think geek sells them now for $20 US: http://www.thinkgeek.com/interests/gamer/be12/ http://www.thinkgeek.com/interests/gamer/be12/

tzs 16y ago
I bought a couple of those out of nostalgia. They aren't very good. The movement is rough, making them kind of annoying to use.
- ajdecon 16y ago
  Agreed. Sphere sells vintage rules though: http://www.sphere.bc.ca/test/sliderule.html http://www.sphere.bc.ca/test/sliderule.html
deleted 16y ago
[deleted]

javanix 16y ago

Despite being cursed with an endless string of horrible (for me - I'm sure some students did well) math classes from high school through college, the one thing I came away from with them was an appreciation of how much more intuitively you can learn mathematics if you don't use a calculator. 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.

JoeAltmaier 16y ago
...and how would you recommend doing logarithms? Thru a table? Why? You would learn approximation techniques, sure, but that teaches you nothing about logarithms, it just spends your time. 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.

jcl 16y ago

The reason that students are required to purchase graphing calculators is for tests, not learning; schools believe they have more control over what goes on during a test if all the students are using the same brand of (locked-down) graphing calculator. 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.

samatman 16y ago
And of course, as every aspiring hacker in high school knows, graphing calculators come with a Turing Complete scripting language that's powerful enough to defeat this stricture for most use cases. 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...

runjake 16y ago

I have a Dietzgen No. 1757. It's useful for raising my Apple external keyboard up to be level with my ergonomic wrist pad. 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?

tokenadult 16y ago
Anyone have any useful links for non-mathematicians learning to use one? http://sliderulemuseum.com/SR_Course.htm http://sliderulemuseum.com/SR_Course.htm http://www.sliderule.ca/intro.htm http://www.sliderule.ca/intro.htm http://www.sphere.bc.ca/test/howto.html http://www.sphere.bc.ca/test/howto.html http://www.hpmuseum.org/srinst.htm http://www.hpmuseum.org/srinst.htm http://thinkgeek.com/files/slide_rule_manual.pdf 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. http://www.ecae.net/2011/02/summer-2011-course-schedule/ http://www.ecae.net/2011/02/summer-2011-course-schedule/
- runjake 16y ago
  Thank you for taking the time to post all of these!

maguro 16y ago

What the hell is this crap doing on Hacker News?!?!?!

jordanb 16y ago

Sliderules can be useful, if you're proficient, for performing repeated calculations where only one variable changes. You can slide the indicator along and produce a series of numbers quickly and easily. 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.

giardini 16y ago

Slide rules enhance understanding of the functions used (mostly logarithm & trig) and require keeping mental track of orders of magnitude(so they help avoid _big_ mistakes in quick calculations). 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.

thinkingeric 16y ago

I use a slide rule regularly. It is neither quick nor accurate, but it is useful in the same way that making approximate calculations in your head is useful. That is to say, added precision doesn't help you understand the relationships in a problem and speed can obscure some of what's interesting. However, this kind of thing is only entertaining and instructive for curious people.

ctdonath 16y ago

Snipers use slide rules. The Mildot Master is popular for computing bullet drop from estimated target size and crosshair grid marks. Sure, some are going to computers for the math, but laminated paper holds up better under extreme conditions for almost free.

vault_ 16y ago

One thing that graphing calculators are really useful for is simple number crunching. In academic settings you frequently need to take down numbers and then compute statistics about them. Tables and matrices are probably the 2 most useful things you can do with a graphing calculator (they're also among the least well known, at least among students). 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.

cafard 16y ago

We probably have two around the house: mine from high school chemistry, one that my wife thinks of as a "proportion wheel" from her days in print production. The proportion wheels were in use with printers and publishers for some years after the nerds had gone to calculators.