$ gdb --core umfpack_simple.core      
[New LWP 101452]
[New LWP 100576]
[New LWP 101450]
[New LWP 101451]
[New LWP 101453]
[New LWP 101454]
[New LWP 101455]
[New LWP 101456]
Core was generated by `./umfpack_simple'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x000000080360ba7d in ?? ()
[Current thread is 1 (LWP 101452)]
(gdb) bt
#0  0x000000080360ba7d in ?? ()
#1  0x00007fffdfbfbe40 in ?? ()
#2  0x00007fffdfbfbe60 in ?? ()
#3  0x0000000000000800 in ?? ()
#4  0x00000000c0000000 in ?? ()
#5  0x00007fffdfbfbe38 in ?? ()
#6  0x0000000b01b303b8 in ?? ()
#7  0x0000000800000018 in ?? ()
#8  0x0000000000004000 in ?? ()
#9  0x0000000801b2e4b0 in ?? ()
#10 0x000000001ffff800 in ?? ()
#11 0x0000000300000001 in ?? ()
#12 0x0000004800000000 in ?? ()
#13 0x0000000000000001 in ?? ()
#14 0x0000001801b2e4c0 in ?? ()
#15 0x0000002000000020 in ?? ()
#16 0x0000002001b2e4b0 in ?? ()
#17 0x0000000000000000 in ?? ()
(gdb) quit