On Wed, 2018-05-09 at 14:17 -0500, Laurence Marks wrote: > You are right, this is a bug (potentially severe). In my local > version I replaced somm with a more standard integration as somm > interpolates to the origin (which is not right).
Will there be a fix for this bug? Best regards Pavel > > On Wed, May 9, 2018 at 2:11 PM, Pavel Ondračka <pavel.ondracka@email. > cz> wrote: > > ---------- Původní e-mail ---------- > > Od: Laurence Marks <[email protected]> > > Komu: A Mailing list for WIEN2k users <[email protected] > > .at> > > Datum: 9. 5. 2018 18:18:21 > > Předmět: Re: [Wien] IEEE_UNDERFLOW_FLAG IEEE_DENORMAL > > > > > Zamt is set by somm, which is a slightly inaccurate Simpson > > > summation (the accuracy does not matter). Hence it does not need > > > to be set previously. > > > > Right, it is indeed set in the somm subroutine. The problem is that > > the DA variable (the local name for zamt variable in the somm > > subroutine) is set for the first time on line 11, while it is used > > (read) for the first time earlier on line 10 (and this is the line > > when the gcc and valgrind complains)! Hence when the subroutine is > > called for the first time, the results depends on read from > > uninitialized memory. > > Best regards > > Pavel > > > > > _____ > > > Professor Laurence Marks > > > "Research is to see what everybody else has seen, and to think > > > what nobody else has thought", Albert Szent-Gyorgi > > > www.numis.northwestern.edu > > > > > > On Wed, May 9, 2018, 10:42 AM Pavel Ondračka <pavel.ondracka@emai > > > l.cz> wrote: > > > > Laurence Marks píše v St 09. 05. 2018 v 11:51 +0000: > > > > > This appears to be due to a silly approach in gfortran, and > > > > almost > > > > > certainly is not an error/problem and can be ignored -- see h > > > > ttps://urldefense.proofpoint.com/v2/url?u=https- > > > > 3A__s&d=DwIGaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r= > > > > U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=R1lxmwh4Y3r4yRx1Z > > > > yR4NN9mpSe7RuaT974qRm6Uhfw&s=KDobN5dacXxTk7OUpO1BdJBY45FBX34Hf6 > > > > Q9hTempg0&e= > > > > > tackoverflow.com/questions/44308577/ieee-underflow-flag-ieee- > > > > > denormal-in-fortran-77. > > > > > > > > > > > > > While I do agree that in most cases this is harmless, it can > > > > also > > > > suggest a bug. > > > > > > > > I only looked at dstart for the TiC and I have this specific > > > > example: > > > > > > > > dstart for a TiC case prints a "Note: The following floating- > > > > point > > > > exceptions are signalling: IEEE_DENORMAL" line. If you trap > > > > this with > > > > -ffpe-trap='denormal' flag, to inspect in gdb, the offending > > > > line is > > > > then: > > > > Program received signal SIGFPE, Arithmetic exception. > > > > 0x000000000041dc48 in somm (dr=..., dp=..., > > > > dpas=0.013585429144994965, > > > > da=1.1588924125005173e-310, m=0, np=935) at somm.f:10 > > > > 10 D1=DA+MM > > > > > > > > so this line looks completely harmless and some prints show why > > > > the > > > > compiler notes about this: > > > > > > > > (gdb) print DA > > > > $1 = 1.1588924125005173e-310 > > > > (gdb) print MM > > > > $2 = 1 > > > > > > > > i.e. we just add a really small number (denormal, since > > > > DOUBLE_MIN is > > > > around 1.8e-308) to 1, which is completely OK. But lets take a > > > > look > > > > where this incredibly small value comes from... > > > > > > > > (gdb) up > > > > #1 0x00000000004143c6 in make_spheres (lcore=.FALSE., luse=7) > > > > at > > > > make_spheres.F:81 > > > > 81 call > > > > somm(rat(1,ia),rhoat(1,ia),dx(ia),zamt,0,nptat(ia)) > > > > > > > > So this is the zamt variable, surprisingly grepping around for > > > > zamt > > > > finds nothing. As far as I can see it is not declared or > > > > initialized > > > > anywere in dstart. If I just missed something please correct > > > > me! The > > > > same goes for the zamt1 and zamt2. > > > > > > > > Note that in this case we get lucky since the random memory > > > > value is > > > > effectively zero, however this might in my opinion lead to > > > > problems if > > > > you hit random memory with another value. > > > > In fact running the dstart in vagrind shows this as well and > > > > the > > > > terminal is spammed with "Conditional jump or move depends on > > > > uninitialised value(s)" and "Use of uninitialised value of size > > > > 8". > > > > > > > > IMO this is a bug, so either the line needs to be changed to > > > > somm(rat(1,ia),rhoat(1,ia),dx(ia),0,0,nptat(ia)) > > > > or the zamt variable needs to be declared and initialized > > > > somewhere. > > > > But I actually have no idea about the physical meaning of the > > > > code so > > > > please correct me if I just missed something. > > > > > > > > Best regards > > > > Pavel > > > > _______________________________________________ > > > > Wien mailing list > > > > [email protected] > > > > https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theoch > > > > em.tuwien.ac.at_mailman_listinfo_wien&d=DwIGaQ&c=yHlS04HhBraes5 > > > > BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnv > > > > qKFdqWLwmqg0&m=R1lxmwh4Y3r4yRx1ZyR4NN9mpSe7RuaT974qRm6Uhfw&s=_8 > > > > Uru9zRH580QrhtgA9HnU1x81x6paXIOqJCFnOzZME&e= > > > > SEARCH the MAILING-LIST at: https://urldefense.proofpoint.com/ > > > > v2/url?u=http-3A__www.mail-2Darchive.com_wien- > > > > 40zeus.theochem.tuwien.ac.at_index.html&d=DwIGaQ&c=yHlS04HhBrae > > > > s5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818j > > > > nvqKFdqWLwmqg0&m=R1lxmwh4Y3r4yRx1ZyR4NN9mpSe7RuaT974qRm6Uhfw&s= > > > > SJYF9VBF7xwkjpCyB76TXcIRXzDcFX3xCQlsoQ4RwIw&e= > > > > > > _______________________________________________ > > > Wien mailing list > > > [email protected] > > > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > > > SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus > > > .theochem.tuwien.ac.at/index.html > > > > _______________________________________________ > Wien mailing list > [email protected] > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > SEARCH the MAILING-LIST at: http://www.mail-archive.com/[email protected] > eochem.tuwien.ac.at/index.html _______________________________________________ Wien mailing list [email protected] http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/[email protected]/index.html
