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From: holiday@boulder.Colorado.EDU (Matthew Holiday)
Newsgroups: comp.lang.fortran
Subject: Re: complex*32?
Message-ID: <16887@boulder.Colorado.EDU>
Date: 13 Feb 90 00:00:59 GMT
References: <1990Feb12.140657.28884@deimos.cis.ksu.edu>
Sender: news@boulder.Colorado.EDU
Reply-To: holiday@tigger.colorado.edu (Matthew Holiday)
Organization: University of Colorado, Boulder
Lines: 23

In article <1990Feb12.140657.28884@deimos.cis.ksu.edu> Myron Calhoun writes:

> ...I vaguely recall the Macintosh meets the first set of criteria.
>
> Also, I question ANYONE'S need for 32 bytes * 8 bits/byte minus
> 12 (bits for exponent and two signs) = 244 bits ~= 74 digits
> of precision!

The Mac (using Language Systems FORTRAN for MPW) offers COMPLEX*20 or
COMPLEX*24, the only difference being that the latter has four bytes
of padding for the math chip.  This means that 80 bits are available
for each of the real and imaginary parts.

Note that the 32 bytes Myron refers to are really split between the
real and imaginary parts, i.e., each is only represented by 16 bytes.
This means you get about 34 digits, minus all the ones eaten up by
the growth of roundoff error.



Matt Holiday                    | "If it were done, when 'tis done,
holiday@tigger.colorado.edu     |  Then 'twere well it were done quickly."
University of Colorado, Boulder |               -- Macbeth I.vii