Comments on: I got your ‘obsolete’ right here, buddy… http://www.decrepitoldfool.com/2006/04/slide_rule_apr06/ Schrodinger's tagline is both clever and banal at the same time Tue, 28 Aug 2012 20:56:43 +0000 hourly 1 http://wordpress.org/?v=3.5.1 By: Newbie http://www.decrepitoldfool.com/2006/04/slide_rule_apr06/#comment-1265 Newbie Sun, 03 Sep 2006 23:52:44 +0000 http://www.decrepitoldfool.com/?p=465#comment-1265 If you’re worried about the third significant digit of precision, I don’t want you designing my bridge! (Though I acknowledge that space flight is another matter entirely.)

]]> By: zilch http://www.decrepitoldfool.com/2006/04/slide_rule_apr06/#comment-1264 zilch Wed, 19 Apr 2006 10:37:38 +0000 http://www.decrepitoldfool.com/?p=465#comment-1264 I still have a circular slide rule I use occasionally.  I agree that three significant digits are nearly always enough, and that using a calculator doesn’t make you think the problem through so that you understand it- my kids often make the most ridiculous errors because of that.

Here’s a significant digit anecdote my father told me:  a co-worker of his requested from the machine shop a block of steel, a “1.000 inch cube”.  The machinist delivered it a couple of days later, commenting that it was a real bitch making a cube accurate to a thousandth of an inch on each side.  The guy who ordered it said “I just need it to prop up a motor housing” and was surprised when the machinist swore at him.  The guy had just thrown in the zeros more or less at random…

]]> By: Lucas Wiman http://www.decrepitoldfool.com/2006/04/slide_rule_apr06/#comment-1263 Lucas Wiman Sun, 16 Apr 2006 09:35:43 +0000 http://www.decrepitoldfool.com/?p=465#comment-1263 Significant digits are usually introduced to people in high school chemistry of physics class.  One of my teachers in HS didn’t really get the reason behind them, insisting that we round at each stage in a calculation.  With modern calculators, it is easier and more precise round at the end, but points would be deducted for giving a more correct answer.

]]> By: Breakerslion http://www.decrepitoldfool.com/2006/04/slide_rule_apr06/#comment-1262 Breakerslion Sat, 15 Apr 2006 18:43:19 +0000 http://www.decrepitoldfool.com/?p=465#comment-1262 “the fact is, no matter how many decimal places appear on the display of your calculator, most likely the incoming data isn’t any more exact than that.”

I wish more people understood the concept of significant digits. I still own my slide rule, but I must admit that it has been 30 years since I’ve used it, and I have forgotten how. Alas, these days a hero is just a sandwich, and a log is just an output file….

]]> By: mostly cajun http://www.decrepitoldfool.com/2006/04/slide_rule_apr06/#comment-1261 mostly cajun Sat, 15 Apr 2006 14:38:53 +0000 http://www.decrepitoldfool.com/?p=465#comment-1261 The three significant digit limitation was never a problem given the accuracy of the data **I** used.  I used to do bridge classification (for weight carrying capability) in the Army with my slide rule.  It was perfect for that.  And jst about everything else.  People today don’t understand that just because you divide one three-decimal place number by another three-decimal place number and the CALCULATOR shows SIX decimal places, that those SIX decimal places are NOT significant.  But it impresses the ignorant…

MC
another old fart…

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