"Strong typing vs. strong testing"
BartC
bc at freeuk.com
Wed Oct 13 03:00:46 CEST 2010
"RG" <rNOSPAMon at flownet.com> wrote in message
news:rNOSPAMon-20651E.17410012102010 at news.albasani.net...
> In article <i92dvd$ada$1 at news.eternal-september.org>,
> "BartC" <bc at freeuk.com> wrote:
>
>> "Thomas A. Russ" <tar at sevak.isi.edu> wrote in message
>> > But radians are dimensionless.
>>
>> But they are still units
>
> No, they aren't.
>
>> so that you can choose to use radians, degrees or gradians
>
> Those aren't units either, any more than a percentage is a unit. They
> are just different ways of writing numbers.
>
> All of the following are the same number written in different notations:
>
> 0.5
> 1/2
> 50%
>
> Likewise, all of the following are the same number written in different
> notations:
>
> pi/2
> pi/2 radians
> 90 degrees
> 100 gradians
> 1/4 circle
> 0.25 circle
> 25% of a circle
> 25% of 2pi
>
> See?
But what exactly *is* this number? Is it 0.25, 1.57 or 90?
I can also write 12 inches, 1 foot, 1/3 yards, 1/5280 miles, 304.8 mm and so
on. They are all the same number, roughly 1/131000000 of the polar
circumference of the Earth.
This does depend on the actual size of an arbitrary circle, but that seems
little different from the choice of 0.25, 1.57 or 90 for your quarter
circle.
--
bartc
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