RE: [boost] Math Constants Library formal review results

From: Paul A. Bristow (pbristow_at_[hidden])
Date: 2001-05-17 16:31:05

> -----Original Message-----
> From: austern_at_[hidden]
> [mailto:austern_at_[hidden]]On Behalf Of Matthew Austern
> Sent: Thursday, May 17, 2001 6:32 PM
> To: boost_at_[hidden]
> Subject: Re: [boost] Math Constants Library formal review results
>
>
> "Paul A. Bristow" wrote:
> >
> > Matt Austern wrote
> >
> > > I'm not convinced that 1 and 0 belong in a numeric constants
> class; they
> > > seem more like things that belong in a numeric type traits
> class, or maybe
> > > even something that's still more general.  There are plenty
> of types for
> > > which you can reasonably ask for the additive or
> multiplicative identity
> > > element, but where these transcendental constants make no sense.
> > > (Integers,
> > > NxN matrices, quaternions,...  There's a sensible "zero" even for
> > > strings.)
> >
> > Agree with what you say
> >
> >  - but since math_constants in a separate namespace,
> > is there any significant disadvantage
> > to having them with other numeric constants?
> > Completeness has some merit?
>
>
> But we don't have completeness.  We never can.
>
> You've got sqrt(2), but not, if I'm remembering right,
> sqrt(3) or sqrt(5).  You've got pi and e, but not, if
> I'm remembering right, Euler's constant (a.k.a. gamma).

(Yes I do have Euler/gamma)

> You don't have the zeros of the Bessel functions.  And
> once you start including derived quantities, there's
> no end to it: do you include pi/2, pi/3, 2*pi, 4*pi,
> a/pi, pi^2...?  How about e^2 (a.k.a. exp(2)), or ln(2),
> or ln(10)?  All of those are useful.
>
> Please note: I'm not criticizing you for providing an
> incomplete selection of constants.  You have to draw
> a line somewhere, and I don't know of any non-arbitrary
> way to draw one.
>
> 			--Matt
>

More can probably easily be added!  I only did the ones I have already used.

But I agree it can go on for ever, so we will have to be guided
by users requests.

Paul