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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()
.)
See section 8.11.9.44 Complex Intrinsic, for information on easily constructing
a COMPLEX
value of arbitrary precision from REAL
arguments.
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