clipka <ano### [at] anonymousorg> wrote:
> Am 18.05.2016 um 23:51 schrieb Anthony D. Baye:
> > Because I know you're both a camera guy and a math guy.
> >
> > I was perusing this site:
> > http://davetrott.com/inventions/double-arm-barn-door-drive/
> >
> > and came across a funny (read: strange) computation: 3 + 2**1/3 which google
> > tells me is the same as 3 + 2^(1/3), except that the website (referencing a
> > magazine article from almost 30 years ago) says is equal to 6.464, which is
> > blatantly wrong unless they're doing something completely different with that
> > double asterisk.
>
> Neither the double asterisk (**) nor the caret (^) are mathematical
> symbols (well, at least not in this context); they are merely
> ASCII-conformant kludges to write mathematical formulae for which ASCII
> lacks proper necessary symbols, and different "schools" exist.
>
> The school currently dominant in prose texts uses the caret to denote
> superscript in general, or exponentiation in particular, with x^y
> therefore denoting "x raised to the y-th power" (e.g. x^2 denoting "x
> squared").
>
> This is quite independent of the use in computer languages: While some
> do use the caret as an exponentiation operator, others use it for a
> bitwise-or. Most notably, all the old-school programming languages like
> Ada, COBOL and FORTRAN used the double asterisk instead.
>
> Thus there is indeed reason to assume that the 30 year-old expression "3
> + 2**1/3" is meant to denote "3 plus the one-third power of 2" or, in
> other words, "3 plus the cubic root of 2". This is far from certain
> though; most notably, in virtually all programming languages that use
> the double-asterisk notation for exponentiation, the expression would be
> interpreted as "3+((2**1)/3)", which doesn't make much sense because the
> exponentiation would be redundant.
>
> Another thing that really doesn't fit is that this expression seems to
> be related to straightforward geometry, and you rarely get a cubic root
> there; what you usually get is plenty of square roots.
>
> As a matter of fact, the alleged result, 6.464, happens to be
> suspiciously close to 3+2*sqrt(3), or 3+2*3**(1/2), which has all of the
> ingredients of the expression in question, albeit arranged differently
> and with an additional factor of 2 thrown in. Since this expression may
> easily arise from a geometric problem, my guess is that the original
> author seriously screwed up the formula when trying to express it in
> ASCII, but that the numeric result is legit.

something tells me they might have been trying to express the equation in terms
of fractional exponents to make up for a lack of radical notation, but it's
still screwy.  And it could be a source error, but considering their result was
verified independently by others, I'm assuming it's a transcription or OCR
error.

Regards,
A.D.B.

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