[mod.computers.vax] Multiple precision arithmetic in FORTRAN

JCV@CERNVM.BITNET.UUCP (04/04/87)

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