<div dir="auto">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.<br><br><div data-smartmail="gmail_signature">_____<br>Professor Laurence Marks<br>"Research is to see what everybody else has seen, and to think what nobody else has thought", Albert Szent-Gyorgi<br><a href="http://www.numis.northwestern.edu">www.numis.northwestern.edu</a></div></div><br><div class="gmail_quote"><div dir="ltr">On Wed, May 9, 2018, 10:42 AM Pavel Ondračka <<a href="mailto:pavel.ondracka@email.cz">pavel.ondracka@email.cz</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Laurence Marks píše v St 09. 05. 2018 v 11:51 +0000:<br>
> This appears to be due to a silly approach in gfortran, and almost<br>
> certainly is not an error/problem and can be ignored -- see <a href="https://urldefense.proofpoint.com/v2/url?u=https-3A__s&d=DwIGaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=R1lxmwh4Y3r4yRx1ZyR4NN9mpSe7RuaT974qRm6Uhfw&s=KDobN5dacXxTk7OUpO1BdJBY45FBX34Hf6Q9hTempg0&e=" rel="noreferrer noreferrer" target="_blank">https://urldefense.proofpoint.com/v2/url?u=https-3A__s&d=DwIGaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=R1lxmwh4Y3r4yRx1ZyR4NN9mpSe7RuaT974qRm6Uhfw&s=KDobN5dacXxTk7OUpO1BdJBY45FBX34Hf6Q9hTempg0&e=</a><br>
> <a href="http://tackoverflow.com/questions/44308577/ieee-underflow-flag-ieee-" rel="noreferrer noreferrer" target="_blank">tackoverflow.com/questions/44308577/ieee-underflow-flag-ieee-</a><br>
> denormal-in-fortran-77.<br>
> <br>
<br>
While I do agree that in most cases this is harmless, it can also<br>
suggest a bug.<br>
<br>
I only looked at dstart for the TiC and I have this specific example:<br>
<br>
dstart for a TiC case prints a "Note: The following floating-point<br>
exceptions are signalling: IEEE_DENORMAL" line. If you trap this with<br>
-ffpe-trap='denormal' flag, to inspect in gdb, the offending line is<br>
then:<br>
Program received signal SIGFPE, Arithmetic exception.<br>
0x000000000041dc48 in somm (dr=..., dp=..., dpas=0.013585429144994965,<br>
da=1.1588924125005173e-310, m=0, np=935) at somm.f:10<br>
10 D1=DA+MM<br>
<br>
so this line looks completely harmless and some prints show why the<br>
compiler notes about this:<br>
<br>
(gdb) print DA<br>
$1 = 1.1588924125005173e-310<br>
(gdb) print MM<br>
$2 = 1<br>
<br>
i.e. we just add a really small number (denormal, since DOUBLE_MIN is<br>
around 1.8e-308) to 1, which is completely OK. But lets take a look<br>
where this incredibly small value comes from...<br>
<br>
(gdb) up<br>
#1 0x00000000004143c6 in make_spheres (lcore=.FALSE., luse=7) at<br>
make_spheres.F:81<br>
81 call<br>
somm(rat(1,ia),rhoat(1,ia),dx(ia),zamt,0,nptat(ia))<br>
<br>
So this is the zamt variable, surprisingly grepping around for zamt<br>
finds nothing. As far as I can see it is not declared or initialized<br>
anywere in dstart. If I just missed something please correct me! The<br>
same goes for the zamt1 and zamt2.<br>
<br>
Note that in this case we get lucky since the random memory value is<br>
effectively zero, however this might in my opinion lead to problems if<br>
you hit random memory with another value.<br>
In fact running the dstart in vagrind shows this as well and the<br>
terminal is spammed with "Conditional jump or move depends on<br>
uninitialised value(s)" and "Use of uninitialised value of size 8".<br>
<br>
IMO this is a bug, so either the line needs to be changed to <br>
somm(rat(1,ia),rhoat(1,ia),dx(ia),0,0,nptat(ia))<br>
or the zamt variable needs to be declared and initialized somewhere.<br>
But I actually have no idea about the physical meaning of the code so<br>
please correct me if I just missed something.<br>
<br>
Best regards<br>
Pavel<br>
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</blockquote></div>