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

Controlling data storage
Increasing default data sizes
Chapter 3112
$ f90 +autodbl4 precision2.f90
$ a.out
Stored in x: 3.14159265358979310000
Stored in y: 3.14159265358979323846
Stored in z: 3.14159265358979310000
Though useful for increasing the range and precision of numerical data, the +autodbl and +autodbl4
options are especially useful when porting; see “Large word size” on page 242. For detailed information
about these options, see the HP Fortran Programmer’s Reference. For detailed information about how
floating-point arithmetic is implemented on HP 9000 computers and how floating-point behavior affects the
programmer, refer to the HP-UX Floating-Point Guide.