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From: JCV@CERNVM.BITNET.UUCP
Newsgroups: mod.computers.vax
Subject: Re: Multiple precision arithmetic in FORTRAN
Message-ID: <8704040537.AA10195@ucbvax.Berkeley.EDU>
Date: Sat, 4-Apr-87 00:37:54 EST
Article-I.D.: ucbvax.8704040537.AA10195
Posted: Sat Apr  4 00:37:54 1987
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Use the library routines LIB$ADDX and LIB$SUBX, respectively, to do the job.
They use the machine instructions ADDWC and SUBWC (add/subtract with carry)
on arrays of longwords, whose size can be specified in the call. See, e.g.,
HELP RTL LIB$ LIB$ADDX for more information.
For comparison of the two values, you'll probably have to write a three line
FORTRAN routine that does the compare by comparing individual elements of
the array.
For bit setting/testing, use the FORTRAN built-ins IBSET/BTEST. See
HELP FORTRAN BUILT-IN ...


-- Jan