From: Gautier <Gautier.deMontmollin@Maths.UniNe.CH>
Subject: Re: Ada95 speed
Date: 1999/05/31
Date: 1999-05-31T00:00:00+00:00 [thread overview]
Message-ID: <3752A1D1.CC20510@Maths.UniNe.CH> (raw)
In-Reply-To: 7ht4ss$4mu$1@nnrp1.deja.com
Robert Dewar wrote:
> > and the removal of the hidden Sqrt helps surely
> > even more...
> Don't assume that a square root is necesarily that expensive.
> On some architectures, square root is comparable in speed
> to a floating-point division, not so terrible ....
OK - but it might be useful to mention to uninformed readers
that generally floating-point division is still terribly slower than
a multiplication or an addition, so in that case a Sqrt less could
improve things.
Here is an excerpt from the Intel(R) Pentium(TM) clock cycle table:
FADD [reg,reg] fadd 3, 1
FADD memreal fadd shortreal 3, 1
FADDP reg,ST faddp st(6),st 3, 1
FIADD memint fiadd int16 7, 4
FMUL [reg,reg] fmul st(5),st 3, 1
FMULP reg,ST fmulp st(6),st 3, 1
FIMUL memint fimul warray[di] 7, 4
FDIV [reg,reg] fdiv st(5),st 39
FDIV memreal fdiv longreal 39
FDIVP reg,ST fdivp st(6),st 39
FIDIV memint didiv warray[di] 42
FDIVR [reg,reg] fdivr st(5),st 39
FDIVR memreal fdivr longreal 39
FDIVRP reg,ST fdivrp st(6),st 39
FIDIVR memint didivr warray[di] 42
FSQRT fsqrt 70
--
Gautier
--------
http://members.xoom.com/gdemont/
next prev parent reply other threads:[~1999-05-31 0:00 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <374182F2.B10AD449@Maths.UniNe.CH>
1999-05-18 0:00 ` Ada95 speed Tom Moran
1999-05-18 0:00 ` Gautier
1999-05-19 0:00 ` Robert Dewar
1999-05-20 0:00 ` Clifford J. Nelson
1999-05-20 0:00 ` Tucker Taft
1999-05-20 0:00 ` Tom Moran
1999-05-20 0:00 ` Tom Moran
1999-05-21 0:00 ` Tom Moran
1999-05-31 0:00 ` James E. Hopper
1999-06-01 0:00 ` Clifford J. Nelson
1999-06-01 0:00 ` James E. Hopper
1999-06-02 0:00 ` Clifford J. Nelson
1999-06-04 0:00 ` Clifford J. Nelson
1999-06-02 0:00 ` James E. Hopper
1999-06-02 0:00 ` Clifford J. Nelson
1999-06-02 0:00 ` James E. Hopper
1999-06-02 0:00 ` Clifford J. Nelson
1999-06-02 0:00 ` Gautier
1999-06-02 0:00 ` John B. Matthews, M.D.
1999-06-03 0:00 ` Ada95 speed (wandering off topic slightly) Dale Stanbrough
1999-06-03 0:00 ` Larry Kilgallen
1999-06-04 0:00 ` Aidan Skinner
1999-06-02 0:00 ` Ada95 speed John B. Matthews, M.D.
1999-06-02 0:00 ` Clifford J. Nelson
1999-06-02 0:00 ` Robert Dewar
1999-06-04 0:00 ` Clifford J. Nelson
1999-06-04 0:00 ` Ole-Hjalmar Kristensen
1999-06-04 0:00 ` David C. Hoos, Sr.
1999-06-01 0:00 ` Clifford J. Nelson
1999-06-01 0:00 ` James E. Hopper
1999-06-02 0:00 ` Robert Dewar
1999-06-04 0:00 ` Clifford J. Nelson
1999-06-05 0:00 ` Robert Dewar
1999-06-03 0:00 ` Robert I. Eachus
1999-05-31 0:00 ` Gautier [this message]
1999-05-19 0:00 ` Robert Dewar
1999-06-07 0:00 Robert I. Eachus
1999-06-07 0:00 ` tmoran
-- strict thread matches above, loose matches on Subject: below --
1999-06-06 0:00 tmoran
1999-06-06 0:00 ` Robert Dewar
1999-06-06 0:00 tmoran
1999-06-06 0:00 ` David C. Hoos, Sr.
1999-06-06 0:00 ` tmoran
1999-06-07 0:00 ` Robert Dewar
1999-06-06 0:00 ` David C. Hoos, Sr.
1999-06-07 0:00 ` Robert Dewar
1999-06-06 0:00 ` Brian Rogoff
1999-06-05 0:00 tmoran
1999-06-05 0:00 ` Robert Dewar
1999-06-05 0:00 ` Ehud Lamm
1999-06-05 0:00 ` William Starner
1999-06-05 0:00 ` Ehud Lamm
1999-06-05 0:00 ` Clifford J. Nelson
1999-06-06 0:00 ` David Botton
1999-06-06 0:00 ` Ehud Lamm
1999-06-07 0:00 ` Robert Dewar
1999-06-07 0:00 ` Ehud Lamm
1999-06-05 0:00 tmoran
1999-06-05 0:00 ` Al Christians
1999-06-05 0:00 ` David C. Hoos, Sr.
1999-05-18 0:00 Clifford J. Nelson
1999-05-17 0:00 ` David Starner
1999-05-18 0:00 ` Clifford J. Nelson
1999-05-18 0:00 ` Larry Kilgallen
1999-05-18 0:00 ` Tucker Taft
1999-05-18 0:00 ` Clifford J. Nelson
1999-05-18 0:00 ` Florian Weimer
1999-05-20 0:00 ` Tom Moran
1999-05-21 0:00 ` Clifford J. Nelson
1999-05-21 0:00 ` Tom Moran
1999-05-21 0:00 ` Clifford J. Nelson
1999-05-21 0:00 ` Tom Moran
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