Hi There, The following code extest.cpp: extern "C" { int ilaenv_( int *ispec, const char *name, const char *uplo, int *N, int *N2, int *N3, int *N4 ); } int main () { int ispec = 1; const char* name = 'DSYTRD'; const char uplo = 'U'; int N = 4; int N2 = -1; int N3 = -1; int N4 = -1; int NB; NB = ilaenv_( &ispec, name, &uplo, &N, &N2, &N3, &N4 ); return 0; } compiled with: g++ -ggdb -L/.../lapack/ extest.cpp -llapack -lblas -lgfortran using g++ 4.4.1, when run under gdb, segfaults at the external function call, giving: Program received signal SIGSEGV, Segmentation fault. _wordcopy_bwd_aligned (dstp=140737353957304, srcp=-130065848, len=2305843009196895680) at wordcopy.c:282 the backtrace yields: #0 _wordcopy_bwd_aligned (dstp=140737353957304, srcp=-130065848, len=2305843009196895680) at wordcopy.c:282 #1 0x00007ffff709ccaa in memmove (dest=0x7fffffffd1f0, src=<value optimized out>, len=18446744073575165448) at memmove.c:99 #2 0x000000000040f7c1 in ilaenv_ () #3 0x00007fffffffda90 in ?? () #4 0x00007fffffffdbf0 in ?? () #5 0x0000000000000002 in ?? () #6 0x00007fffffffdbf0 in ?? () #7 0x00007fffffffd25f in ?? () #8 0x00007fffffffda60 in ?? () #9 0x0000000000000000 in ?? () I have only a faint idea of what wordcopy.c does, but I'm guessing that the length parameter here is perhaps a bit large. I thought I'd post here in case there's a known issue with wordcopy.c. Thanks, -David