Once upon a time, I saw a pamphlet in a tuxedo-rental shop. It
explained that back in Edwardian days, "anybody who was anybody"
owned their own formal wear. However, it went on to say, back in
those days "almost nobody was anybody".
I mention that because on 03/14/2012 07:05 AM, chuck britton wrote:
Ah, for the Good Old Days when everything was done to 'Slide Rule Accuracy'.
That's a really good point.
When I was 4 years old, my father gave me a slide rule and taught me
how to use it.
According to that slide rule, 8.9 / 7.8 is 1.14 ... which does not
conform to the usual "textbook" sig-figs rules. It would be monumentally
foolish to round off the answer from 1.14 to 1.1.
Ten years later, when I got to high school chemistry, they tried to
teach us about sig figs, but I was completely immune. I already knew
how to do calculations, real calculations where people cared about the
answer. When we students encountered sig figs, we just rolled our eyes
and reminded ourselves of the slogan: Chemistry class, where we go to
learn things that cannot possibly be true.
Note that the sig-figs disease is very unevenly distributed. In some
experiments described at http://www.ncsu.edu/PER/Articles/DeardorffDissertation.pdf
at one institution, 11% of the students reported the uncertainty
separately and explicitly, while at another nearby institution 73%
did. On the other hand, there are so many things in that document
that don't add up that it is hard to trust any of it. On the third
hand, the 73%/11% ratio is consistent with my personal anecdotal
observations, so I'm predisposed to believe it.
Back in the Old Days when "anybody who was anybody" used a slide rule, it
was obvious that the quotient 1.14 needed more digits than the numerator
or denominator, and it was obvious why.
However, back in those days, anybody who knew how to use a slide rule
was in a very small minority. The slide rule was the badge and symbol
of geekdom.
Nowadays a lot more people can perform calculations. Non-geeks can use
calculators and spreadsheets. It is possible for people who don't entirely
understand the principles involved to crunch their own numbers. IMHO
this is /mostly/ a good thing. By way of analogy, a lot of people who
don't understand the internal workings of a car are allowed to drive cars,
and this is mostly a good thing.
================
You can do a lot with a slide rule.
Remember that things like the Saturn V and the SR-71 were almost entirely
slide-rule designs.