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Groups > comp.sys.raspberry-pi > #12761
| From | mm0fmf <none@invalid.com> |
|---|---|
| Newsgroups | comp.sys.raspberry-pi, comp.lang.forth |
| Subject | Re: Jazelle? |
| Date | 2016-07-20 17:39 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <nmo9fg$flm$2@dont-email.me> (permalink) |
| References | (3 earlier) <MPG.31f93e8b429c8383989804@172.16.0.1> <nmnge0$rri$1@dont-email.me> <2016Jul20.121415@mips.complang.tuwien.ac.at> <nmnvi0$e7s$1@dont-email.me> <2016Jul20.163523@mips.complang.tuwien.ac.at> |
Cross-posted to 2 groups.
On 20/07/2016 15:35, Anton Ertl wrote:
> "gareth G4SDW GQRP #3339" <no.spam@thank.you.invalid> writes:
>> "Anton Ertl" <anton@mips.complang.tuwien.ac.at> wrote in message
>> news:2016Jul20.121415@mips.complang.tuwien.ac.at...
>>> "gareth G4SDW GQRP #3339" <no.spam@thank.you.invalid> writes:
>>>> Consider the solution of the quadratic equation expressed in
>>>> a HLL ...
>>>>
>>>> X = (-B + SQRT ( B**2 - 4*A*C))?2*A
>>>
>>> Which HLL uses "?" as division operator that has lower priority than
>>> "*"; actually, which HLL has a division operator with lower priority
>>> than "*"?
>>
>> A minor typo caused by typing with the shift key held down
>>
>> And, yes, S/B (2*A) but neither critique answers the HLL versus assembler
>> criticism.
>
> "S/B (2*A)"?
>
> What "HLL vs. assembler criticism"?
>
> If your example was an attempt to show the superiority of the Fortran
> notation over the Forth notation, then the fact that you made two
> errors in this one line was not a good testimonial for the Fortran
> way.
>
>>> Anyway, this way of computing one of the solutions for a quadratic
>>> equation is bad because it introduces more numerical instability than
>>> is coming from the problem itself. Read more about how to do it
>>> better in
>>
>> Not relevant to demonsrtating the ease of use and built in syntax checking
>> of a HLL compared to an assembler.
>
> So you want to demonstrate the superiority of the Fortran notation
> with an example that no competent Fortran programmer will write in
> that way? And then you parenthesize it incorrectly, a mistake that
> will not be detected by "syntax checking".
>
> Interestingly, in <913374461.4045.0.nnrp-04.9e98250c@news.demon.co.uk>
> (from 1998) Gareth Alun Evans (any relation to you?) gave pretty much
> the same example (in BASIC syntax, though), and made the same
> parenthesis omission mistake. Not a testimonial for the qualities of
> infix syntax.
>
> If you write the example in a numerically stable way, you get several
> smaller statements rather than a big one, more like most real
> programs, and the difference between infix and postfix becomes
> smaller. I guess that's why you choose this example; apparently it's
> hard to come up with another huge formula that many people can relate
> to. So even if the Fortran notation would be better for writing down
> one solution of a quadratic equation in a numerically unstable way
> (and the mistakes of you and Gareth Alun Evans are evidence against
> this thesis), that says little about the quality of that notation for
> real (and competently written) programs.
>
> Anyway, here's a way to compute the roots (if they are real) without
> the numeric instability (you still have bad condition when bb/4 and ac
> cancel each other out, so you may want to compute that part with higher
> precision).
>
> : compute-q { f: a f: b/2 f: c -- q }
> b/2 b/2 f* a c f* f- fsqrt
> b/2 f0< if fnegate then \ avoids cancelation by the F+ below
> b/2 f+ ;
>
> : quadratic { f: a f: b f: c -- x1 x2 }
> a b f2/ c compute-q { f: q }
> q a f/ c q f/ ;
>
> - anton
>
Oh dear, you'll be on Gareth's enemy list now.
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Jazelle? "gareth G4SDW GQRP #3339" <no.spam@thank.you.invalid> - 2016-07-18 10:50 +0100
Re: Jazelle? rickman <gnuarm@gmail.com> - 2016-07-19 20:25 -0400
Re: Jazelle? The Natural Philosopher <tnp@invalid.invalid> - 2016-07-20 07:08 +0100
Re: Jazelle? Paul <paul@pcserviceselectronics.co.uk> - 2016-07-20 08:54 +0100
Re: Jazelle? The Natural Philosopher <tnp@invalid.invalid> - 2016-07-20 09:29 +0100
Re: Jazelle? Gordon Henderson <gordon+usenet@drogon.net> - 2016-07-20 12:56 +0000
Re: Jazelle? "gareth G4SDW GQRP #3339" <no.spam@thank.you.invalid> - 2016-07-20 14:54 +0100
Re: Jazelle? Folderol <general@musically.me.uk> - 2016-07-20 18:40 +0100
Re: Jazelle? The Natural Philosopher <tnp@invalid.invalid> - 2016-07-20 19:12 +0100
Re: Jazelle? rickman <gnuarm@gmail.com> - 2016-07-20 15:17 -0400
Re: Jazelle? "gareth G4SDW GQRP #3339" <no.spam@thank.you.invalid> - 2016-07-20 20:32 +0100
Re: Jazelle? rickman <gnuarm@gmail.com> - 2016-07-20 15:37 -0400
CAN / LIN auto bus (was Jazelle?) jeffj@panix.com (Jeff Jonas) - 2016-07-20 17:53 -0400
Re: CAN / LIN auto bus (was Jazelle?) Martin Gregorie <martin@address-in-sig.invalid> - 2016-07-20 22:28 +0000
Re: CAN / LIN auto bus (was Jazelle?) druck <news@druck.org.uk> - 2016-07-20 23:37 +0100
Re: Jazelle? alister <alister.ware@ntlworld.com> - 2016-07-20 13:34 +0000
Re: Jazelle? rickman <gnuarm@gmail.com> - 2016-07-20 10:26 -0400
Re: Jazelle? Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-07-20 19:51 -0400
Re: Jazelle? "gareth G4SDW GQRP #3339" <no.spam@thank.you.invalid> - 2016-07-20 10:31 +0100
Re: Jazelle? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-07-20 10:14 +0000
Re: Jazelle? "gareth G4SDW GQRP #3339" <no.spam@thank.you.invalid> - 2016-07-20 14:49 +0100
Re: Jazelle? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-07-20 14:35 +0000
Re: Jazelle? mm0fmf <none@invalid.com> - 2016-07-20 17:39 +0100
Re: Jazelle? "gareth G4SDW GQRP #3339" <no.spam@thank.you.invalid> - 2016-07-20 20:30 +0100
Re: Jazelle? rickman <gnuarm@gmail.com> - 2016-07-20 15:35 -0400
Re: Jazelle? "WJ" <w_a_x_man@yahoo.com> - 2016-07-21 10:43 +0000
Re: Jazelle? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-07-21 12:44 +0000
Re: Jazelle? "gareth G4SDW GQRP #3339" <no.spam@thank.you.invalid> - 2016-07-21 22:59 +0100
Re: Jazelle? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-07-22 06:42 +0000
Re: Jazelle? "gareth G4SDW GQRP #3339" <no.spam@thank.you.invalid> - 2016-07-22 12:03 +0100
Re: Jazelle? rickman <gnuarm@gmail.com> - 2016-07-22 09:05 -0400
Re: Jazelle? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-07-22 19:20 +0300
Re: Jazelle? "WJ" <w_a_x_man@yahoo.com> - 2016-07-25 10:43 +0000
Re: Jazelle? "gareth G4SDW GQRP #3339" <no.spam@thank.you.invalid> - 2016-07-26 11:41 +0100
Re: Jazelle? Doug Hoffman <glidedog@gmail.com> - 2016-07-20 06:44 -0400
Re: Jazelle? "gareth G4SDW GQRP #3339" <no.spam@thank.you.invalid> - 2016-07-20 14:52 +0100
Re: Jazelle? rickman <gnuarm@gmail.com> - 2016-07-20 10:52 -0400
Re: Jazelle? alister <alister.ware@ntlworld.com> - 2016-07-20 15:40 +0000
Re: Jazelle? rickman <gnuarm@gmail.com> - 2016-07-20 11:46 -0400
Re: Jazelle? Robert Riches <spamtrap42@jacob21819.net> - 2016-07-21 01:27 +0000
Re: Jazelle? "A. Dumas" <alexandre@dumas.fr.invalid> - 2016-07-21 05:58 +0200
Re: Jazelle? colonel_hack@yahoo.com - 2016-07-21 16:29 -0700
Re: Jazelle? "A. Dumas" <alexandre@dumas.fr.invalid> - 2016-07-22 01:56 +0200
Re: Jazelle? colonel_hack@yahoo.com - 2016-07-22 14:04 -0700
Re: Jazelle? "gareth G4SDW GQRP #3339" <no.spam@thank.you.invalid> - 2016-07-22 11:59 +0100
Re: Jazelle? rickman <gnuarm@gmail.com> - 2016-07-20 10:56 -0400
Re: Jazelle? rickman <gnuarm@gmail.com> - 2016-07-20 10:24 -0400
Re: Jazelle? Theo Markettos <theom+news@chiark.greenend.org.uk> - 2016-07-20 14:38 +0100
Re: Jazelle? "gareth G4SDW GQRP #3339" <no.spam@thank.you.invalid> - 2016-07-20 14:57 +0100
Re: Jazelle? rickman <gnuarm@gmail.com> - 2016-07-20 10:53 -0400
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