On 6/12/2010 12:07 AM, Hans Jørgen Aagaard Jensen wrote:
The NINT() intrinsic in current gfortran under cygwin has a bug. Below follows:
1) small test program
2) output from this program
3) output from "gfortran -v"
(I am not submitting this to the gcc bugzilla, because the test worked OK on
all the linux systems I tested.)
(I found the error becaus our quantum chemistry softward dirac
(http://dirac.chem.sdu.dk) failed a few of the internal tests.)
-- Hans Jørgen Aa. Jensen
======= 1) small test program ============
program test
double precision xval
xval = 132843.61283756854D0
do i = 1,7
ipoint = nint(xval)
write (6,*), xval, ipoint
xval = 10.0d0*xval
end do
return
end
======= 1) output =============
132843.61283756854 132844
1328436.1283756853 -1596096578
Try the following replacement for nint():
ipoint = xval+.5
which leads me to believe the lround function from newlib is buggy.
If you wished to handle negative as well as positive, the work-around
ipoint = xval+sign(.5,xval)
would take it a little further. This short-cuts the distinction between
ieee_nearest and legacy Fortran rounding style, but I don't see that
gfortran was making the distinction.
--
Tim Prince
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