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# Digital slide rule

For the 0.4999999 baker
 (+28, -1) [vote for, against]

There is something mathematically tactile about slide rules - the way that you can just slide one wooden scale against another and mutliply, divide, find roots...it makes mathematics physically real in a way that a calculator does not. I doubt if anyone cherishes their calculator the way that engineers used to cherish their slide rule.

Slide rules also encourage you to actually think about what you're doing: you have to figure out where the decimal point belongs in your answer.

Unfortunately, they lack the irrelevant precision of the pocket calculator, and can become inaccurate with wear and tear.

Enter the MaxCo Digital Slide Rule. It combines the precision of a digital micrometer with the mathematical capabilities of a slide rule. As you slide the centre strip and cursor, their positions are displayed digitally (on the cursor itself). Should its batteries run out, it will function quite satisfactorially as a regular slide rule until you replace them.

 — MaxwellBuchanan, Dec 07 2007

Slide rule..... http://en.wikipedia.org/wiki/Slide_rule
[MaxwellBuchanan, Dec 07 2007]

...digital micometer... http://www.shan-precision.com/sxkc_1.htm
[MaxwellBuchanan, Dec 07 2007]

..and a combination of the two. Digital_20slide_20rule
[MaxwellBuchanan, Dec 07 2007]

(?) USB calipers http://www.everythi..._usb_interface.html
Avoid typing in the numbers like 0.4999999 .... [csea, Dec 08 2007]

(?) CS Student Wins Yahoo! Hack Day with Digital Slide Rule http://www.cs.uiuc....php?id=2007Apr9-251
"It's pretty clear that he's one of the top students in terms of being able to think things through," Kumar said. "His clarity of thinking is actually very, very special." I assume you thought up this idea all by yourself, so that praise befits you as well [MaxwellBuchanan]. [pyggy potamus, Dec 08 2007]

As bloody usual, there's an app for that http://www.testtube....com/sliderule.html
[bs0u0155, Apr 12 2016]

 Bravo! + Also for the phrase "mathematically tactile."

A version of this could include USB connection to a computer, like this one [link].
 — csea, Dec 08 2007

 I would love to have one of these. I think you could probably sell quite a few of them. I also don't think it would be too difficult to make a relatively simple one.

Bake it! There are quite a few hardware hack project sites on the web - I suspect if you get visible on one of those you might have some luck. Great idea.
 — husband_of_bath, Dec 08 2007

Good point, [csea]. I just hope there's an OSX- compatible loglog version available. And thanks, [husband].
 — MaxwellBuchanan, Dec 08 2007

 I noticed that Hackaday has a place where you can suggest a project -

I've no idea if this is a good place to go, I've seen some sites that had fairly detailed how-to for some cute home electronics projects, and I suspect that some of those have features that enable you to pair up with someone who knows what they're doing. Seriously, I'd love to have one of these things.
 — husband_of_bath, Dec 08 2007

That is a nice site - thanks :-)
 — MaxwellBuchanan, Dec 08 2007

 A not so accurate version would use a calibrated resistor and wiper, with an analogue circuit and a moving needle display: 0.48 isn't so bad.

+
 — Ling, Dec 08 2007

 "Trixie Tang: You're 0.01% more of a person in my eyes." - quote from the Fairly Odd Parents cartoon.

now i know what measuring tool she used. [+]
 — pyggy potamus, Dec 08 2007

This gets my vote ... anything that isn't dependant on batteries. And for good measure you could add a little photovoltaic panel to keep the battery topped up. [+]
 — 8th of 7, Dec 08 2007

[Pyggy] Aha! Well, all praise to young Schecter. With respect, though, I feel that his on-screen slide-rule lacks a little of the tactile feel and portability of the MaxCo Digital Slide Rule.
 — MaxwellBuchanan, Dec 08 2007

 //With respect, though, I feel that his on-screen slide-rule lacks a little of the tactile feel and portability of the MaxCo Digital Slide Rule.//

i agree. indubitably!
 — pyggy potamus, Dec 08 2007

Maybe there could be a slide rule display on TI-89's so that people can see the process what it's doing every time it does something. [+]
 — quantum_flux, Dec 10 2007

 Rather than replacing batteries, you could generate power from the motion of the slide rule center part through its frame.

I don't think this is easy. There are a number of unsolved user-interface details. On a real slide rule you know what things mean, or you look in the right place - the digital slide rule may have to know this implicit information in order to correctly e.g. store an intermediate result.
 — jutta, Dec 10 2007

 //There are a number of unsolved user- interface questions// Indeed so - I have found this to be the case with life in general.

 Typically, the things you need to know are (a) which number on the central slider [I can't believe there's not a special name for that, but there you go] is aligned with the "1" on the static scales (which normally have a common origin) and (b) which numbers on each scale are underneath the cursor hairline. I think all this data could be displayed on the cursor itself - which is typically postage-stamp to matchbox sized. For example, there is room to display the value which the cursor crosses on each of the scales - the values would appear superimposed on top of the corresponding scales.

 There are more complex cases, but I think the foregoing would serve as a good starting point.

 I could post a more detailed and elegantly-drawn picture of the MaxCo Digital Slide Rule if only I had a site to host it. And if only I had such a picture.

Regarding energy production by sliding - I rather like that idea. Embedded magnets and coils would be the obvious way to do it, but I think it would be more in the spirit of things if we could use amber, short-piled mole-fur and some sort of high-voltage rectifier.
 — MaxwellBuchanan, Dec 10 2007

Incidentally, it goes without saying that a small amount of additional electronics would allow this to function as a polyphonic swannee whistle.
 — MaxwellBuchanan, Dec 10 2007

 Eeek! Did I just delete someone's annotation - apologies if so. I was resonding to:

//Is not a swannee whistle by definition polyphonic ?// No, it is not. You can only get one note at a time out of a swannee whistle (variable though that note may be). With a slide rule, you have both a cursor and a slidey bit to move - biphony, at least.
 — MaxwellBuchanan, Dec 10 2007

And for tonight's recital, we have [MaxwellBuchanan] on the slide rule <applause>
<sings> Six times seven is <fweep peep> forty two
and two to-the-power-of five is <peeep fwip> thirty two
and...</sings>

Ugh ... this would be the Music of the Slides rather than the Music of the Spheres .... music crushed and tortured into two miserable dimensions .....
 — 8th of 7, Dec 10 2007

//music crushed and tortured into two miserable dimensions// Yes, this is why I said it went without saying.
 — MaxwellBuchanan, Dec 10 2007

 //some sort of high-voltage rectifier//

(Commonly known as a cat's whisker, or rather uncommonly now, I suppose).
 — Ling, Dec 11 2007

 //(Commonly known as a cat's whisker, or rather uncommonly now, I suppose).//

 [Ling], [Ling], [Ling], I have heretofore relied upon you for sensible advice; shirley you recall that cat's whiskers and galena crystals are suitable only for rectification of extremely low voltages!

[MB]'s //amber, short-piled mole-fur // stroked by rapid slipsticking would seem to produce a rather high voltage. Besides which, I'm fairly sure that the voltage generated by rubbing mole fur on amber is already dc, in need of no rectification. But perhaps I am off-topic!
 — csea, Dec 11 2007

//the voltage generated by rubbing mole fur on amber is already dc, in need of no rectification.// After extensive experimentation, I can confirm that this is correct. The mole always winds up with the negative charge. I currently have three moles stuck to the ceiling - any advice greatly appreciated.
 — MaxwellBuchanan, Dec 11 2007

 //I have heretofore relied upon you for sensible advice//

Now I see you have come to your senses.
 — Ling, Dec 11 2007

 [MB] Three moles (1.806x10^24) of what?

 (I did that with my mental digital slide rule, and had to remember where the decimal point goes!)

[Ling] Not to worry. If I had _really_ come to my senses, would I still be at the halfbakery?
 — csea, Dec 12 2007

//Three moles (1.806x10^24) of what// Good point. Actually, it's five yoctomoles of moles.
 — MaxwellBuchanan, Dec 12 2007

<snort> <chortle> <guffaw> What would you <snort> Oh hells! (+)
 — elhigh, Dec 12 2007

+ in response to <ahem>
 — pashute, Apr 11 2016

Ideally, it would also project an image on the user's face of a pair of glasses held together by tape.
 — Ander, Apr 12 2016

 //There are a number of unsolved user-interface details.//

At its simplest, all the gubbins would be in the cursor (the slidey transparent bit with the hairline on it). If there are (say) four scales (two on the moving central part, and one either side on the fixed part), the cursor would have four numerical displays showing exactly where it was on each scale. For instance, you might see that the cursor was lined up at 3.45-something on the topmost scale and 10.16-something on the second scale, but the digital readouts would show it to be at exactly 3.45433 and 10.16231 respectively.
 — MaxwellBuchanan, Apr 12 2016

 I'm thumbing this on a not-so-smartphone. It's relation, in the guise of a Samsung Note, has an under-used pen which pulls out from the case. This might be a place for an extending sliderule, with digits displayed on the phone.

However, I am afraid it would be a poor use of the scientific calculator program, and the sliderule would be quite small. So I suggest that the program be deleted and the battery shrunk to a smaller size.
 — Ling, Apr 13 2016

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