From: robert_dewar@my-dejanews.com
Subject: Re: Calculating SQRT in ADA
Date: 1999/03/25
Date: 1999-03-25T00:00:00+00:00 [thread overview]
Message-ID: <7dbv6t$4u5$1@nnrp1.dejanews.com> (raw)
In-Reply-To: 19990324125518.01416.00000432@ngol08.aol.com
In article <19990324125518.01416.00000432@ngol08.aol.com>,
johnherro@aol.com (John Herro) wrote:
> Here's a generic square root routine in Ada 83, taken
from my AdaTutor program:
>
> generic
> type Dummy is digits <>;
> function Sqrt(X :in Dummy) return Dummy;
> function Sqrt(X :in Dummy) return Dummy is
> Guess : Dummy := X;
> begin
> if X < 0.0 then
> raise Constraint_Error;
> end if;
> while X /= 0.0 and then
> abs(Guess*Guess/X - 1.0) > 3.0*Dummy'Epsilon loop
> Guess := (X/Guess + Guess) * 0.5;
> end loop;
> return Guess;
> end Sqrt;
Why the epsilon test, this iteration will terminate to
exact equality in any reasonable floating-point model,
and you cannot guarantee the 3*epsilon convergence if
the floating-point model is silly anyway.
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next prev parent reply other threads:[~1999-03-25 0:00 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-03-24 0:00 Calculating SQRT in ADA cmcrae
1999-03-23 0:00 ` Chris Morgan
1999-03-24 0:00 ` Marin David Condic
[not found] ` <36F913E0.75F51763@lmco.com>
1999-03-24 0:00 ` Ada 83 - Sometimes still chosen Richard D Riehle
1999-03-25 0:00 ` robert_dewar
1999-03-25 0:00 ` Richard D Riehle
1999-03-25 0:00 ` Marin David Condic
1999-03-26 0:00 ` robert_dewar
1999-03-25 0:00 ` robert_dewar
1999-03-25 0:00 ` Richard D Riehle
1999-03-25 0:00 ` Larry Kilgallen
1999-03-26 0:00 ` robert_dewar
1999-03-26 0:00 ` Tarjei Tj�stheim Jensen
1999-03-27 0:00 ` robert_dewar
1999-03-27 0:00 ` Tarjei Tj�stheim Jensen
1999-03-26 0:00 ` Tom Moran
1999-03-26 0:00 ` Richard D Riehle
1999-03-26 0:00 ` Tom Moran
1999-03-26 0:00 ` Larry Kilgallen
1999-03-29 0:00 ` Marin David Condic
1999-03-29 0:00 ` Tarjei Tj�stheim Jensen
1999-03-27 0:00 ` Matthew Heaney
1999-03-24 0:00 ` Calculating SQRT in ADA John Herro
1999-03-24 0:00 ` Hans Marqvardsen
[not found] ` <36FAA3DF.42C31CF@lmco.com>
1999-03-26 0:00 ` Tom Moran
1999-03-25 0:00 ` robert_dewar
1999-03-25 0:00 ` robert_dewar [this message]
1999-03-25 0:00 ` John Herro
1999-03-24 0:00 ` Hans Marqvardsen
1999-03-25 0:00 ` David C. Hoos, Sr.
1999-03-25 0:00 ` robert_dewar
1999-03-25 0:00 ` David C. Hoos, Sr.
1999-03-26 0:00 ` Howard W. LUDWIG
1999-03-26 0:00 ` Ole-Hjalmar Kristensen
1999-03-27 0:00 ` robert_dewar
1999-03-29 0:00 ` Robert I. Eachus
1999-03-30 0:00 ` robert_dewar
1999-04-02 0:00 ` Robert I. Eachus
1999-03-30 0:00 ` robert_dewar
1999-04-02 0:00 ` Robert I. Eachus
1999-04-03 0:00 ` robert_dewar
1999-03-25 0:00 ` robert_dewar
1999-03-26 0:00 ` Calculating SQRT in Ada John Herro
1999-03-26 0:00 ` David C. Hoos, Sr.
1999-03-26 0:00 ` John Herro
1999-03-25 0:00 ` Calculating SQRT in ADA robert_dewar
1999-03-24 0:00 ` Howard W. LUDWIG
1999-03-25 0:00 ` Larry Kilgallen
1999-03-24 0:00 ` bob
1999-03-24 0:00 ` Niklas Holsti
1999-03-26 0:00 ` als0045
1999-03-26 0:00 ` als0045
1999-03-26 0:00 ` bob
1999-03-26 0:00 ` Marin David Condic
1999-03-26 0:00 ` David C. Hoos, Sr.
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