HP Fortran Programmer's Guide (September 2007)

Compiling and linking

Compiling with the f90 command

Chapter 228

REAL*8 D

3.1416_4, 113_4

Note, however, that constants speciﬁed with an exponent—for example,

4.0E0 and 2.3D0—are doubled.

Items promoted include constants, scalar variables, arrays, components of

derived types, and record ﬁelds. This option also promotes intrinsics as well

as the results and arguments of user-deﬁned functions to the proper

precision. Types speciﬁed in ON statements are also promoted.

The entire program should be compiled with this option, not just selected

ﬁles.

This option is useful when porting programs that depend on the increased

precision of 8 and 16 bytes. If you want to promote only single-precision

items, use the +autodbl4 option. (REAL(KIND=16) arithmetic is slow.)

The default is +noautodbl.

+[no]autodbl4

Like +autodbl, +auotdbl4 increases the default size of integer, logical, and

real items to 8 bytes, and the default size of complex items to 16 bytes; see

Table 2-3. Unlike +autodbl, it does not increase the default size of double

precision.

This option does not increase the size of the following:

INTEGER(KIND=4)

INTEGER(4) J

REAL*8 D

Table 2-3 Data type sizes and +autodbl[4]

Sizes in bytes of intrinsic types

Integer,

logical,

and real

Double

precision

Complex

Default sizes 4 8 8

+autodbl 81616

+autodbl4 8816