# COMPLEX(8) or DOUBLE COMPLEX Constants

A COMPLEX(8) or DOUBLE COMPLEX constant is a pair of constants that represents a complex number. One of the pair must be a double-precision real constant, the other can be an integer, single-precision real, or double-precision real constant.

A COMPLEX(8) or DOUBLE COMPLEX constant occupies 16 bytes of memory and is interpreted as a complex number.

The rules for DOUBLE PRECISION (REAL(8)) constants also apply to the double precision portion of COMPLEX(8) or DOUBLE COMPLEX constants. (See General Rules for Complex Constants and REAL(8) or DOUBLE PRECISION Constants for the rules on forming DOUBLE PRECISION constants.)

The DOUBLE PRECISION constants in a COMPLEX(8) or DOUBLE COMPLEX constant have IEEE* binary64 format.

The default KIND for DOUBLE COMPLEX is affected by compiler option double-size.

## Examples

Valid COMPLEX(8) or DOUBLE COMPLEX Constants
`(1.7039,-1.7039D0)`
`(547.3E0_8,-1.44_8)`
`(1.7039E0,-1.7039D0)`
`(+12739D3,0.D0)`

Invalid COMPLEX(8) or DOUBLE COMPLEX Constants
`(1.23D0,)` | Second constant missing.
`(1D1,2H12)` | Hollerith constants not allowed.
`(1,1.2)` | Neither constant is DOUBLE PRECISION; this is a valid single-precision constant.

Parent topic: Complex Data Types

## See Also

General Rules for Complex Constants
double-size