I think I mentioned this to several PETSc folks two years ago. It is a bad idea to return complex numbers from Fortran, as there is no portable solution as far as I know; some compilers need you to declare it as complex zdotc_( <regular args> ) some as void zdotc_( <regular args>, complex* z ) and I think I ran into problems with both on OSX (but don't quote me on it). I ended up settling on writing my own complex dotc and dotu routines. Jack On Sat, Feb 18, 2012 at 5:28 PM, Matthew Knepley <[email protected]> wrote:

We have a problem with complex dot product on OSX. Here is the easiest way to see it (I think):

knepley:/PETSc3/petsc/petsc-dev$ ./arch-complex-fftw-debug/lib/ex5-obj/ex5 -snes_monitor ./arch-complex-fftw-debug/lib/ex5-obj/ex5 -snes_monitor 0 SNES Function norm 0.000000000000e+00

With the debugger:

Breakpoint 1, VecNorm_Seq (xin=0x1022fc170, type=NORM_2, z=0x7fff5fbfea10) at bvec2.c:238 238 ierr = VecGetArrayRead(xin,&xx);CHKERRQ(ierr); (gdb) n Current language: auto; currently c++ 239 *z = BLASdot_(&bn,xx,&one,xx,&one); (gdb) p bn $1 = 16 (gdb) p xx[0]@16 $2 = {{ _M_value = 0 + 0 * I }, { _M_value = 0 + 0 * I }, { _M_value = 0 + 0 * I }, { _M_value = 0 + 0 * I }, { _M_value = 0 + 0 * I }, { _M_value = -0.10378182131158753 + 0 * I }, { _M_value = -0.10378182131158753 + 0 * I }, { _M_value = 0 + 0 * I }, { _M_value = 0 + 0 * I }, { _M_value = -0.10378182131158753 + 0 * I }, { _M_value = -0.10378182131158753 + 0 * I }, { _M_value = 0 + 0 * I }, { _M_value = 0 + 0 * I }, { _M_value = 0 + 0 * I }, { _M_value = 0 + 0 * I }, { _M_value = 0 + 0 * I }} (gdb) p one $3 = 1 (gdb) n 240 *z = PetscSqrtReal(*z); (gdb) p *z $4 = 0 (gdb) p zdotc $5 = {<text variable, no debug info>} 0x7fff863e71e2 <zdotc_>

It appears that the dot product is producing nothing. Didn't we have a similar problem a little while ago?

Matt

-- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener