On Fri, Nov 20, 2015 at 6:07 PM, Hugo Siles <[email protected]> wrote: > Hello, > > I have installed espresso-5.2.1 on fedora 22, with some minor difficulties, > but it has been installed, I run all the tests, and as far as I could see > all of them passed. > However when running one of the samples from the tutorials with the > following command: > pw.x <Si.sample.in> Si.sample.out > I get the following message during execution: > > [hsiles@localhost exercise1]$ pw.x <Si.sample.in> Si.sample.out > Note: The following floating-point exceptions are signalling: > IEEE_INVALID_FLAG IEEE_DENORMAL. > > There is an output file > > Does the message means any thing to worry about ??
yes and no. the messages by itself are harmless. either of the two signaled cases can happen in normal calculations. however, they also indicate that you may be subject to a significant performance penalty due to how the GNU C library and compilers manage your floating point unit. often the difference is rather small, but in pathological cases, the difference can be substantial. since you are running on a desktop machine, i would not worry too much. this is usually avoided by using, e.g. a custom math library (libm) and BLAS library and also a compiler that bypasses a lot of the "lets-be-as-correct-as-possible-even-if-it-doesn't-make-sense-for-most-people" nonsense the GNU people seem to love so much. axel. > > > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum -- Dr. Axel Kohlmeyer [email protected] http://goo.gl/1wk0 College of Science & Technology, Temple University, Philadelphia PA, USA International Centre for Theoretical Physics, Trieste. Italy. _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
