default ndiag
What is the reason behind the parent_nproc/2? I feel it is more natural to have just parent_nproc as default although achieving the best performance may require tuning ndiag for big runs.
! no command-line argument -ndiag N or -northo N is present
! insert here custom architecture specific default definitions
#if defined __SCALAPACK
nproc_ortho_try = MAX( parent_nproc/2, 1 )
#else
nproc_ortho_try = 1
#endif