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(g77-295.info)DCmplx Intrinsic

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DCmplx Intrinsic
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     DCmplx(X, Y)

DCmplx: `COMPLEX(KIND=2)' function.

X: `INTEGER', `REAL', or `COMPLEX'; scalar; INTENT(IN).

Y: `INTEGER' or `REAL'; OPTIONAL (must be omitted if X is `COMPLEX');
scalar; INTENT(IN).

Intrinsic groups: `f2c', `vxt'.

Description:

   If X is not type `COMPLEX', constructs a value of type
`COMPLEX(KIND=2)' from the real and imaginary values specified by X and
Y, respectively.  If Y is omitted, `0D0' is assumed.

   If X is type `COMPLEX', converts it to type `COMPLEX(KIND=2)'.

   Although this intrinsic is not standard Fortran, it is a popular
extension offered by many compilers that support `DOUBLE COMPLEX',
since it offers the easiest way to convert to `DOUBLE COMPLEX' without
using Fortran 90 features (such as the `KIND=' argument to the
`CMPLX()' intrinsic).

   (`CMPLX(0D0, 0D0)' returns a single-precision `COMPLEX' result, as
required by standard FORTRAN 77.  That's why so many compilers provide
`DCMPLX()', since `DCMPLX(0D0, 0D0)' returns a `DOUBLE COMPLEX' result.
Still, `DCMPLX()' converts even `REAL*16' arguments to their `REAL*8'
equivalents in most dialects of Fortran, so neither it nor `CMPLX()'
allow easy construction of arbitrary-precision values without
potentially forcing a conversion involving extending or reducing
precision.  GNU Fortran provides such an intrinsic, called `COMPLEX()'.)

   Note: Complex Intrinsic, for information on easily constructing a
`COMPLEX' value of arbitrary precision from `REAL' arguments.