Intel® Fortran Compiler Classic and Intel® Fortran Compiler Developer Guide and Reference

ID 767251
Date 3/22/2024
Public

A newer version of this document is available. Customers should click here to go to the newest version.

Document Table of Contents

DOUBLE PRECISION

Statement: Specifies the DOUBLE PRECISION data type.

DOUBLE PRECISION

A REAL(8) or DOUBLE PRECISION constant has more than twice the accuracy of a REAL(4) number, and greater range.

A REAL(8) or DOUBLE PRECISION constant occupies eight bytes of memory. The number of digits that precede the exponent is unlimited, but typically only the leftmost 15 digits are significant.

IEEE* binary64 format is used.

For more information, see General Rules for Real Constants.

Example

DOUBLE PRECISION varnam
DOUBLE PRECISION,PRIVATE :: zz
Valid REAL(8) or DOUBLE PRECISION constants

123456789D+5

123456789E+5_8

+2.7843D00

-.522D-12

2E200_8

2.3_8

3.4E7_8

Invalid REAL(8) or DOUBLE PRECISION constants

-.25D0_2

2 is not a valid kind type for reals.

+2.7182812846182

No D exponent designator is present; this is a valid single-precision constant.

123456789.D400

Too large for any double-precision format.

123456789.D-400

Too small for any double-precision format.