HP Fortran Programmer's Guide (September 2007)

Compiling and linking
Compiling with the f90 command
Chapter 2 37
+[no]fp_exception
+fp_exception is a compile time flag. It causes a descriptive message and a
procedure traceback to be issued to standard error when the HP-UX signals
listed in Table 2-5 are generated.
For a description of these signals, see signal (2) and signal (5) in the
HP-UX Reference. For information about floating-point exceptions and error
handling, see the HP-UX Floating-Point Guide.
You can also use the ON statement to write your own trap procedures. For
information about the syntax of the ON statement, see “Using the ON
statement” on page 125.
The default, +nofp_exception, disables traceback information.
D Enable sudden underflow (flush to zero) of denormalized
values on those PA-RISC systems greater than version 1.0
that have implemented sudden underflow. (That is, +FPD
enables sudden underflow only if it is available on the
processor that is used at run time.) Denormalized values
are those values whose absolute value is very close to zero.
For IEEE single precision data types, the largest
denormalized value is approximately equal to 2
-126
. For
IEEE double precision data types, such values are
approximately equal to 2
-1022
. Sudden underflow will cause
some floating-point applications to run faster, with a
possible loss of numerical accuracy on numbers very close to
zero.
Table 2-5 Signals recognized by the +fp_exception option
Signal Meaning
SIGILL Illegal instruction
SIGFPE Floating-point exception
SIGBUS Bus error instruction
SIGSEGV Segmentation violation
Table 2-4 Values for the +FP option (Continued)
Value Meaning