Maths constants
in [Fortran]
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From: Simon Geard on 20 Jan 2010 05:11 On 19/01/2010 20:31, Richard Maine wrote: > Paul Hirose <jvcmz89uwf(a)earINVALIDthlink.net> wrote: > >> Nowadays even a budget Windows machine does floating point in hardware >> per the IEEE standard, so I believe arc cosine of -1 is a safe way to >> compute pi, for example. However, I'd be interested to hear of any >> cases where this would have caused trouble. > > Ouch! Ouch! Ouch! > > Hey, Fortran is often used for numeric stuff and us folk are supposed to > have at least a surface acquaintance with issues of numeric accuracy. > <snip> > I use literals. > Which makes me wonder why there aren't intrinsic parameters to go with intrinsic functions. Presumably they have been suggested for possible inclusion in f90, 95, 2003 and 2008 but rejected. Simon
From: Les Neilson on 20 Jan 2010 05:42 "Simon Geard" <simon(a)whiteowl.co.uk> wrote in message news:hj6krv$nj0$1(a)news.eternal-september.org... > On 19/01/2010 20:31, Richard Maine wrote: <snip> > > Which makes me wonder why there aren't intrinsic parameters to go with > intrinsic functions. Presumably they have been suggested for possible > inclusion in f90, 95, 2003 and 2008 but rejected. > > Simon The first difficulty would be specifying a *finite* list of constants (there are rather a lot across the sciences that I can think of and presumably plenty more of which I am unaware or have forgotten - someone's favourite constant being left out might cause a diplomatic incident!) Then there are those constants which are continually being refined to greater accuracy. Compiler vendors have enough to do without having to keep track of changes to the accepted value for something. But it was a nice thought :-) Les
From: Gordon Sande on 20 Jan 2010 08:51 On 2010-01-20 06:42:25 -0400, "Les Neilson" <l.neilson(a)nospam.co.uk> said: > > "Simon Geard" <simon(a)whiteowl.co.uk> wrote in message > news:hj6krv$nj0$1(a)news.eternal-september.org... >> On 19/01/2010 20:31, Richard Maine wrote: > <snip> >> >> Which makes me wonder why there aren't intrinsic parameters to go with >> intrinsic functions. Presumably they have been suggested for possible >> inclusion in f90, 95, 2003 and 2008 but rejected. >> >> Simon > > The first difficulty would be specifying a *finite* list of constants > (there are rather a lot across the sciences that I can think of and > presumably plenty more of which I am unaware or have forgotten - > someone's favourite constant being left out might cause a diplomatic > incident!) > > Then there are those constants which are continually being refined to > greater accuracy. When was the last time that the value of the mathematical constant pi was changed? Or any other mathematical constant for that matter. The legal (not mathematical) value of pi used for computing real estate frontages of curved properties does not count as that value is well known to be 4 in some jurisdictions! > Compiler vendors have enough to do without having to keep track of > changes to the accepted value for something. > > But it was a nice thought :-) > > Les
From: user1 on 20 Jan 2010 09:11 Gordon Sande wrote: > > When was the last time that the value of the mathematical constant pi > was changed? Indiana House Bill No. 246, 1897 unsuccessful?
From: Dan Nagle on 20 Jan 2010 09:13
Hello, On 2010-01-20 05:42:25 -0500, "Les Neilson" <l.neilson(a)nospam.co.uk> said: > "Simon Geard" <simon(a)whiteowl.co.uk> wrote in message > news:hj6krv$nj0$1(a)news.eternal-september.org... >> Which makes me wonder why there aren't intrinsic parameters to go with >> intrinsic functions. Presumably they have been suggested for possible >> inclusion in f90, 95, 2003 and 2008 but rejected. > The first difficulty would be specifying a *finite* list of constants > (there are rather a lot across the sciences that I can think of and > presumably plenty more of which I am unaware or have forgotten - > someone's favourite constant being left out might cause a diplomatic > incident!) > > Then there are those constants which are continually being refined to > greater accuracy. Compiler vendors have enough to do without having to > keep track of changes to the accepted value for something. Leaving aside the issue of mathematical versus physical constants, it has been considered, and rejected. The issue was the difficulty of anticipating the intended use of the constant. Is it to be used as a threshold, or a sentinel, or a conversion factor, or something else? Absent a convincing answer to the above question, the proposals were shelved for lack of resources on the standards committees. YMMV -- Cheers! Dan Nagle |