# f90_kind: KIND Number Parameters Module

## 1
Name

`f90_kind` — Module providing useful KIND number parameters
## 2
Usage

**USE F90_KIND**

## 3
Synopsis

**Parameters**
- SINGLE,
DOUBLE,
QUAD,
REAL32,
REAL64,
REAL64x2,
REAL128,
INT8,
INT16,
INT32,
INT64,
BYTE,
TWOBYTE,
WORD,
LOGICAL64,
ASCII.

## 4
Parameter Description

INTEGER,PARAMETER :: SINGLE

For `REAL` and `COMPLEX`, selects the default real or default complex
kind; this is equivalent to leaving the `KIND` selector off entirely.

INTEGER,PARAMETER :: DOUBLE

Selects the double precision real kind; this is equivalent to declaring
`REAL` entities using the `DOUBLE PRECISION` type specifier, to
declaring `COMPLEX` entities using `COMPLEX(KIND(0d0))`, and to using
the exponent letter `D` on literal constants.

INTEGER,PARAMETER :: QUAD

`REAL`/`COMPLEX` kind selector for real and complex types with
approximately twice the precision of `DOUBLE`.
This might not be available on some systems; on a system without this type, the
value of this parameter will be negative.

INTEGER,PARAMETER :: REAL32

`REAL`/`COMPLEX` kind selector for real and complex types that are
represented using 32-bit floating-point numbers.

INTEGER,PARAMETER :: REAL64

`REAL`/`COMPLEX` kind selector for real and complex types that are
represented using 64-bit floating-point numbers.

INTEGER,PARAMETER :: REAL64x2

`REAL`/`COMPLEX` kind selector for real and complex types that are
represented using “double-double” floating-point numbers.
A double-double floating-point number consists of two 64-bit values, one of
which is at least `DIGITS(1._REAL64)` smaller than the other; this has
almost twice the precision of `REAL64` (except when near zero), but a
smaller exponent range.
This type is not available on all systems; on a system without this type, the
value of this parameter is −1.

INTEGER,PARAMETER :: REAL128

`REAL`/`COMPLEX` kind selector for real and complex types that are
represented using 128-bit floating-point numbers.
This will select a “true 128-bit” floating-point type if one is
available, and if not it will select a “double-double” floating-point
type if that is available; if no 128-bit floating-point type is available the
value of this parameter is -1.

INTEGER,PARAMETER :: INT8

`INTEGER` kind selector for integer types with at least 8 bits of
precision.

INTEGER,PARAMETER :: INT16

`INTEGER` kind selector for integer types with at least 16 bits of
precision.

INTEGER,PARAMETER :: INT32

`INTEGER` kind selector for integer types with at least 32 bits of
precision.

INTEGER,PARAMETER :: INT64

`INTEGER` kind selector for integer types with at least 64 bits of
precision.

INTEGER,PARAMETER :: BYTE

`LOGICAL` kind selector for logical types occupying only one byte of
memory.

INTEGER,PARAMETER :: TWOBYTE

`LOGICAL` kind selector for logical types occupying the same space as
`INTEGER(INT16)` entities.

INTEGER,PARAMETER :: WORD

`LOGICAL` kind selector for a 32-bit logical type.

INTEGER,PARAMETER :: LOGICAL64

`LOGICAL` kind selector for a 64-bit logical type.
INTEGER,PARAMETER :: ASCII

`CHARACTER` kind selector for the ASCII character set.
## 5
Notes

The source code for this module can be found in the NAG Fortran runtime library
directory (on Unix this is usually ‘`/usr/local/lib/NAG_Fortran`’
or ‘`/opt/NAG_Fortran/lib`’, and on Windows it is usually
‘`C:\Program Files\NAG\EFBuilderPro\NAG_Fortran\lib`’).

## 6
See Also

**nagfor**(1),
**nag_modules**(3).

## 7
Bugs

Please report any bugs found to ‘support@nag.co.uk’ or
‘support@nag.com’, along with any suggestions for improvements.