Re: floating point exceptions: Linux kernel feature or bug?
Hi,
Your message about the floating point exception sounds related
to a problem I have. For me it appears to be an underflow. Keep me
posted if you find a solution.
Thank you,
aaron
I am running Persistance of Vision ray tracer (povray) compiled on
[amj@testnode branch]$ uname -a
Linux testnode.math.ukans.edu 2.1.96 #2 SMP Thu Apr 16 19:05:54 CDT 1998 alpha unknown
[amj@testnode branch]$ gcc --version
2.7.2.3
This code generates a picture as output using Intel-Linux and IRIX 6.3
[amj@testnode branch]$ gdb ~/bin/povray.debug
(gdb) run +L/home/amj/thesis/povray3/include +Imov +KFF1 +FP
Starting program: /home/amj/bin/povray.debug +L/home/amj/thesis/povray3/include +Imov +KFF1 +FP
<irrelevant povray output deleted>
Parsing...........
Creating bounding slabs.
Scene contains 1 frame level objects; 0 infinite.
00:00:00 so far, Rendering frame 1, going to 1.
Rendering...
Program received signal SIGFPE, Arithmetic exception.
0x120045dcc in do_specular (Finish=0x120211ce0, Light_Source_Ray=0x11fffec38,
REye=0x11ffff5d8, Layer_Normal=0x11ffff6e0, Colour=0x11ffff758,
Light_Colour=0x11ffff5f0, Layer_Pigment_Colour=0x11ffff710)
at ../lighting.c:1688
1688 Intensity = Finish->Specular * pow(Cos_Angle_Of_Incidence, Finish->Roughness);
(gdb) list 1680
1675
1676 VHalf(Halfway, REye, Light_Source_Ray->Direction);
1677
1678 VLength(Halfway_Length, Halfway);
1679
1680 if (Halfway_Length > 0.0)
1681 {
1682 VDot(Cos_Angle_Of_Incidence, Halfway, Layer_Normal);
1683
1684 Cos_Angle_Of_Incidence /= Halfway_Length;
(gdb)
1685
1686 if (Cos_Angle_Of_Incidence > 0.0)
1687 {
1688 Intensity = Finish->Specular * pow(Cos_Angle_Of_Incidence, Finish->Roughness);
1689
1690 if (Finish->Metallic > 0.0)
1691 {
1692 /*
1693 * Calculate the reflected color by interpolating between
1694 * the light source color and the surface color according
(gdb) p Halfway_Length
$1 = 0.7136288436493563
(gdb) p Cos_Angle_Of_Incidence
$2 = 0.49138409073828376
(gdb) p Intensity
$3 = 2.3872427115046736e-314
(gdb)
Don't know the gdb syntax to print values within structure Finish->
------------------------------------------------------------------------------
End of output while not running inside gdb:
------------------------------------------------------------------------------
Parsing...........
Creating bounding slabs.
Scene contains 1 frame level objects; 0 infinite.
00:00:01 so far, Rendering frame 1, going to 1.
make: *** [frames] Floating point exception (core dumped)
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