Re: Dimensionality Checking (Ada 20XX)

["Mark Lundquist" <mlundquist2@attbi.com>]

"Stephen Leake" <stephen.a.leake.1@gsfc.nasa.gov> wrote in message
news:upu5ln22l.fsf@gsfc.nasa.gov...
>
> It is simply wrong to try to define units for trig and exponential
> functions. Remember the Taylor expansion for Sin:
>
> Sin (x) = x - 1/6 x**3 ...
>
> If x has dimensions of meters (shudder :), then what are the
> dimensions of Sin (x)?

Hokey smokes, it's the ratio of two sides of a triangle, so its dimensions
are Distance/Distance!  Forget the Taylor series!

> This is why angles must be dimensionless, as
> radians are.

Angles are not dimensionless.  They are the ratio of distance around the
circumference to the radius.  That's why for radian, there's 2 * Pi of 'em
in a circle.  The SI defines the units of radians as (m * m**-1) ('m' stands
for 'meters').  I don't get why people keep saying radians are
dimensionless.

Cheers,
Mark