Is this a bug of ifc 7.1

Intel® Fortran Compiler

Build applications that can scale for the future with optimized code designed for Intel® Xeon® and compatible processors.

Is this a bug of ifc 7.1

193 Views

program main
real*8 eps(4),a12,a34
eps(1) = Z'4037CB020C49BA5E'
eps(2) = Z'403C1E76C8B43958'
eps(3) = Z'BFF943D46B26BF87'
eps(4) = Z'BFF943D46B26BF87'
write(*,'(z17.16)') eps(1)*eps(2) - eps(3)*eps(4)
a12 = eps(1)*eps(2)
a34 = eps(3)*eps(4)
write(*,'(z17.16)') a12 - a34
end

save this program as ex5.f and compile it with ifc -o ex5 ex5.f
then you can see the difference, why????

Anybody can give me an explanation? In java I got the second result, and also I believe the second one is correct! But how to change the first expression correct by changing some options of ifc?

Link Copied

0 Replies

Community support is provided during standard business hours (Monday to Friday 7AM - 5PM PST). Other contact methods are available here.

Intel does not verify all solutions, including but not limited to any file transfers that may appear in this community. Accordingly, Intel disclaims all express and implied warranties, including without limitation, the implied warranties of merchantability, fitness for a particular purpose, and non-infringement, as well as any warranty arising from course of performance, course of dealing, or usage in trade.

For more complete information about compiler optimizations, see our Optimization Notice.