transfer from real to logical
in [Fortran]
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From: Harold Stevens on 10 Dec 2009 06:08 In <hfq11u$ioq$1(a)naig.caltech.edu> glen herrmannsfeldt: [Snip...] > an architecture exists even if no implementations of it still exist FWIW... I appreciate the extensive historical as well as technical expertise and experience in clf. FWIW (Sequel)... It's looking like "frank" might be a "robin" sockpuppet. JMO; YMMV... -- Regards, Weird (Harold Stevens) * IMPORTANT EMAIL INFO FOLLOWS * Pardon any bogus email addresses (wookie) in place for spambots. Really, it's (wyrd) at airmail, dotted with net. DO NOT SPAM IT. I toss GoogleGroup (http://twovoyagers.com/improve-usenet.org/).
From: Frank on 11 Dec 2009 23:30 On Thu, 10 Dec 2009 05:08:59 -0600, Harold Stevens wrote: > In <hfq11u$ioq$1(a)naig.caltech.edu> glen herrmannsfeldt: > > [Snip...] > >> an architecture exists even if no implementations of it still exist > > FWIW... > > I appreciate the extensive historical as well as technical expertise and > experience in clf. > > FWIW (Sequel)... > > It's looking like "frank" might be a "robin" sockpuppet. JMO; YMMV... Do you ever post code? You're not even good as the self-annointed ng policeman. You see if I were betting on someone being a sockpuppet, it would be you, and I would think your better half is one that contributes to building understanding in fortran. -- frank "
From: steve on 12 Dec 2009 10:42 On Dec 7, 3:16 am, Dan Nagle <danna...(a)verizon.net> wrote: > Hello, > > On 2009-12-07 03:13:50 -0500, Frank <fr...(a)example.invalid> said: > > > Do C and Fortran have the same bit > > model for a float/default real? > > Hardware encodes floating point. > > A program written in either C or Fortran, > running on particular hardware, will use the supported > encoding (or it will execute very slowly). > > The languages do not have encodings. > The languages tell you how to access the facilities > of IEEE 754, if available. > > The languages may tell you the effects of operations, > but not how the operations are done. > The above is of course true, but there is a different answer if one interprets Frank's 'same bit model' to mean the model numbers as encoded in Sec. 13. The answer then becomes a little more complicated. The model number for REAL in Fortran and for float in C are the same for normal numbers. C, however, includes exceptional values as well as subnormal numbers (although n1336.pdf calls these unnormalized numbers). See 5.2.4.2.2 Characteristics of floating types <float.h> in n1336.pdf. -- steve
From: steve on 12 Dec 2009 10:45 On Dec 7, 12:13 am, Frank <fr...(a)example.invalid> wrote: > On Fri, 4 Dec 2009 17:16:19 -0500, Dan Nagle wrote: > > Hello, > > > On 2009-12-04 15:23:47 -0500, frank <fr...(a)example.invalid> said: > > > <snip bits from a logical> > > >> Does that look right? > > > It's either right or wrong, depending. > > > Logicals have two values, true and false. > > These may be encoded at the processor's whim. > > > I have seen zero v nonzero, positive v negative, > > even v odd, and probably something else I can't recall. > > > Others have, no doubt, seen other encodings. > > > That way are dragons. > > This shakes my faith a little bit. Do C and Fortran have the same bit > model for a float/default real? > Well, I've read this entire thread, and once again I'm confused by what you're trying to accomplish. laptop:kargl[224] cat a.c b.f90 #include <stdio.h> void cfcn_(float *x) { union a { int i; float x; } u; u.x = *x; printf("%d %x %f %a\n", u.i, u.i, u.x, u.x); } program a external cfcn real x integer i x = 3.141526 call cfcn(x) i = transfer(x,i) print '(I0,1X,Z8,1X,F8.6)', i, i, x end program a laptop:kargl[225] cc -c a.c laptop:kargl[226] gfc4x -o z b.f90 a.o laptop:kargl[227] ./z 1078529731 40490ec3 3.141526 0x1.921d86p+1 1078529731 40490EC3 3.141526 Note, Fortran appears to lack an edit desciptor that corresponds to C %a. -- steve
From: robin on 14 Dec 2009 09:47
"glen herrmannsfeldt" <gah(a)ugcs.caltech.edu> wrote in message news:hfpnfi$gue$1(a)naig.caltech.edu... | robin <robin_v(a)bigpond.com> wrote: | | > The mantissa sign could be anywhere, but it usually is at the left, | > in order that a simple hardware instruction can inspect it | > (in point of fact, typically the same hardware or microcode that inspects | > the sign of an integer). | | And of course it isn't for VAX... We wern't talking specifically about VAX. In any case, that's why I said "usually", because some machines have the bits in reverse order, with the most-significant bit towards the right-hand end, and the sign at the right -- for both integers and reals. |