[R-390] Slide rule calculations

[Grant Youngman]

Those young enough to have grown up on calculators and who view  
sliderules as ancient technology frequently forget about "digits of  
precision" vs. "accuracy" since their handy calculator app or pretty  
display gives them all kinds of numbers to the right of the decimal  
point.   You may get answers "accurate" to 12 or more decimal places,  
but you can't get more digits of precision out than you enter.

In the end, 3.12/9.7 is NOT 0.321649484536....    It is 0.32.  Digits  
of precision in = digits of precision out.  This, of course, applies  
equally to sliderule calculations,  electronic calculator thingies, or  
computers with 128-bit  or more floating point arithmetic.

Grant/NQ5T

On Dec 5, 2008, at 10:58 AM, Gregory W.Moore wrote:

>
> The discussion concerning the good old slipstick, along with one's  
> book
> of logs and trig functions brought back some great memories.  Bob, you
> are dead right that the larger the sliderule, the greater the order of
> magnitude while solving equations.
>
> This being said, and having learned my Engineering on a Pickett 12"  
> rule
> and having solved many, many equations with same, including beating  
> the
> pants off a guy using one of the early scientific calculators, I can
> truly say that you can get 5 places of accuracy if you look closely
> enough.