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<2e75a863-a094-4eb8-a7de-603cf3f5a2dbn@googlegroups.com> 9b4eb26f
@REPLYADDR Ron Shepard <nospam@nowhere.org>
@REPLYTO 2:5075/128 Ron Shepard
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On 8/31/23 7:40 AM, gah4 wrote:
> I believe that they had to support software double precision to
satisfy the standard,
> even if nobody used it.
The ANSI f77 standard book was published so that when you opened a page,
the left hand side of the book was the standard subset, and the right
hand side page was the full standard. If I remember correctly, the
standard subset did not require support for double precision, complex,
or character types. I used a fortran compiler in the early 1980s that
supported complex and character but not double precision. Its REAL type
was 64-bit, so as you say, most programmers did not really need 128-bit
double precision. A subsequent compiler revision did eventually support
128-bit double precision using a mix of hardware and software, so it was
slow.
Nowadays, the de facto standard is that REAL is REAL32, which then means
that REAL64 is DOUBLE PRECISION. I do not know of any compiler in use
these days that contradicts that convention (unless compiler options are
specified). I doubt that the standard will incorporate that convention
due to the backwards compatibility issue and to the possibility that
someone might still want to write a modern fortran compiler for legacy
36-bit, 60-bit, or 64-bit hardware.
$.02 -Ron Shepard
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