HP Fortran Programmer's Guide (B3908-90031; September 2011)

Compiling and linking
Compiling with the f90 command
Chapter 2 39
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 sudden underflow available, while others do not.
The +FPD option enables the hardware to flush denormalized values to zero, but it does
not require that it do so.
Table 2-4 Values for the +FP option
Value Meaning
V Trap on invalid floating-point operations. Examples of invalid
floating-point operations include the following:
• Arithmetic operation on NaNs
• Operations such as (+inf) + (-inf) and (+inf) -
(+inf)
• Multiplication of 0 and infinity
• Division operations 0/0 and inf/inf
• Certain floating-point remainder operations
• Square root of a negative value
• Certain kinds of comparisons of unordered values
Z Trap on floating-point divide by zero.
O Trap on floating-point overflow.
U Trap on floating-point underflow.
I Trap on floating-point operations that produce inexact results.
Inexact result traps may occur whenever roundoff is necessary to
produce the result. For example, the fraction 1.0/3.0 produces an
inexact trap because there is no exact floating-point representation for
this fraction.