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2.16 Data Types

The table below lists the intrinsic data types provided by the NAG Fortran Compiler together with their kind numbers. There are three possible schemes for the intrinsic kind type parameters: the default mode of operation (which may be specified explicitly by the -kind=sequential option), the “byte” numbering scheme (specified by the -kind=byte option) and the “unique” numbering scheme (specified by the -kind=unique).

Type KIND Number KIND Number KIND Number Name Description
Name (sequential) (byte) (unique)
REAL 1 4 301 REAL32* Single precision floating-point
REAL 2 8 302 REAL64* Double precision floating-point
REAL 3 16 303 REAL128* Quad precision floating-point
COMPLEX 1 4 301 REAL32* Single precision complex
COMPLEX 2 8 302 REAL64* Double precision complex
COMPLEX 3 16 303 REAL128* Quadruple precision complex
LOGICAL 1 1 201 BYTE Single byte logical
LOGICAL 2 2 202 TWOBYTE Double byte logical
LOGICAL 3 4 203 WORD Default logical
LOGICAL 4 8 204 LOGICAL64 Eight byte logical
INTEGER 1 1 101 INT8* 8-bit integer
INTEGER 2 2 102 INT16* 16-bit integer
INTEGER 3 4 103 INT32* 32-bit (default) integer
INTEGER 4 8 104 INT64* 64-bit integer
CHARACTER 1 1 646 ASCII ASCII or ISO 8859-1 character
CHARACTER 2 2 213 JIS JIS X 0213 character
CHARACTER 3 3 5323 UCS2 Unicode (UCS-2) character
CHARACTER 4 4 10646 UCS4 ISO 10646 (UCS-4) character

The Name column of the table indicates the name provided by the intrinsic module F90_KIND; the ones marked * are also provided by the standard intrinsic module ISO_FORTRAN_ENV. Using these names avoids the portability problems that arise if the kind numbers are hard-coded.

Note that on all machines except Sun Solaris with the SunPro C compiler, quadruple precision is actually “double double” precision; this provides nearly twice the precision of Double precision but with a reduced exponent range.