Re: Ada versus PL/I (was: Re: Ariane 5 - not an exception?)

["Marin David Condic, 407.796.8997, M/S 731-93" <condicma@PWFL.COM>]

"J. Kanze" <kanze@GABI-SOFT.FR> writes:
>> ---In Fortran, BASIC, Pascal, Algol, PL/I, Turbo C, you just
>> use it [SQRT].  Nothing special needed.
>
>This isn't true for C (and thus Turbo C), of course.  You have to
>include math.h.  While it is a built in in older lanugages like Fortran
>or Basic, most modern languages will require a declaration for the
>function somewhere.  (I'm tempted to say that a language that doesn't
>require a declaration for a function is somewhat deficient, but SQRT is
>a special case.)
>
    Well here's a point that ought to be considered before deciding if
    SQRT should be intrinsic or declared somewhere:

    Ada was (and still is) intended to serve the needs of embedded
    programming. (Yes! yes! yes! You can *still* use it to print
    paychecks and it works just fine!) In embedded systems, you are
    frequently limited in the amount of memory you have available and
    so you don't like to drag along lots of extra functions &
    procedures which will never be called. I've built or seen *LOTS* of
    embedded software which *NEVER* does any arithmetic more
    complicated than +, -, * and /. Hence you'd like to exclude things
    like SQRT, LOG, SIN, etc. as well as any other code that might be
    "intrinsic" in some other language. Making those routines live in
    a "with'ed" package has got to make this job a lot easier.

    I'm not really up on the latest "Linker" theory, but I'd be
    willing to bet that it is a lot simpler to never include an unused
    math package than it is to get a linker to find unused "intrinsic"
    functions built into the RTK and remove them as "dead code".
    Perhaps someone out there a little bit smarter than me can shed
    some light on it? Is it theoretically possible for a linker to
    find *all* unused code and eliminate it? Are most language
    compiler/linker combinations in use today going through
    appropriate gyrations to do this? (A plausible argument for not
    building packages with a bazillion functions in them?)

    MDC

Marin David Condic, Senior Computer Engineer    ATT:        407.796.8997
M/S 731-96                                      Technet:    796.8997
Pratt & Whitney, GESP                           Fax:        407.796.4669
P.O. Box 109600                                 Internet:   CONDICMA@PWFL.COM
West Palm Beach, FL 33410-9600                  Internet:   CONDIC@FLINET.COM
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