HP Fortran Programmer's Guide (September 2007)

Compiling and linking
Compiling with the f90 command
Chapter 2 35
+fastallocatable enables a different representation for allocatable arrays
in the object code produced by the compiler. This alternate representation
avoids problems in optimizing code containing allocatable array references.
Additionally, this alternate representation for allocatable arrays is binary
compatible with the old representation.
+FP flags
+FP initializes the flags that specify how runtime floating-point exceptions
should be trapped; uppercase flags enable traps, lowercase flags disable
traps. flags can be concatenated to specify a desired behavior and may not
contain spaces or tabs. Valid values for flags are identified in Table 2-4.
By default, all traps are disabled. However, you can specifically disable a
behavior either by excluding the upper-case letter from flags or by
including the equivalent lower-case letter (v,z,o,u,i,d) in flags . For
example, the following command lines are equivalent:
$ f90 +FPvZI test.f90
$ f90 +FPZI test.f90
If you are using PA1.1 libraries, you can dynamically change these settings
at run time by using the fpsetdefaults or fpsetmask routines. For more
information about these routines, see the fpgetround (3M) man page and
the
HP-UX Floating-Point Guide.
Enabling sudden underflow may cause the same program to compute
different results on different implementations of the PA-RISC 1.1 and 2.0
architectures. This is because some hardware implementations have