Re: RPN (was Re: TI-83+)
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Re: RPN (was Re: TI-83+)
Tom Lake <tomlake@slic.com> wrote in message
xcTV2.48$I11.1367@newsfeed.slurp.net">news:xcTV2.48$I11.1367@newsfeed.slurp.net...
> Back in the '70s when HP and TI were really competing against each other
in
> the programmable calculator market, an HP brochure made a point that
really
> seems to be true: TI's calculator language (back then called Algebraic
> Operating System or AOS) lets you enter an equation as it's written. HP's
> RPN lets you enter an equation as you would solve it with pencil and
paper.
These are interesting points. In the 70s I bought my first real
programmable calculator, the TI SR56. The manual made much of the
superiority of AOS over RPN, and to prove the point, gave a fairly complex
algebraic expression, full of brackets, exponents, division by differences
and the like, all under a giant root sign. Using the calculator and the
instructions to key in exactly as the expression was written, I got the
wrong answer - four times in a row. A friend had lent me his HP25, which
he'd bought in Switzerland, and the manual was in German, so it was pretty
useless to me. I tried the HP25 on the TI manual's expression, and got it
right first time. As you've indicated, I simply had to work out the answer
from the inside out, because I already knew what the rules of precedence
were for evaluating such expressions by pencil and paper.
Going back to the SR56, the problem I'd had was in counting the number of
open brackets at various stages of the calculation - the expression TI had
chosen to exemplify its argument was just a little too ambitious, and it was
easy for the eye to get confused about where it was in counting brackets and
so forth. Once I'd got used to the AOS syntax for keystroke entry, and
familiarity took over, I didn't have many problems, and I came to regret
selling the SR56 some years later.
Alex
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