EXP(3M) Last changed: 1-6-98
NAME
EXP, DEXP, CEXP, CDEXP - Computes exponential function
SYNOPSIS
UNICOS and UNICOS/mk systems:
EXP ([X=]x)
DEXP ([X=]x)
CEXP ([X=]x)
UNICOS and IRIX systems:
CDEXP ([X=]x)
IMPLEMENTATION
UNICOS, UNICOS/mk, and IRIX systems
STANDARDS
Fortran 90
CDEXP is a compiler extension to Fortran 90.
DESCRIPTION
EXP is the generic function name. EXP, DEXP, and CEXP are elemental
functions for the CF90 compiler.
The entry point CDEXP is provided for support in other languages. It
is not recognized as an intrinsic function; therefore, you must use
the CDIR$ VFUNCTION directive to allow vectorization.
A vector version of this intrinsic exists on UNICOS and UNICOS/mk
systems. On UNICOS/mk systems, the vector version of this intrinsic
is used when -h vector3 (C) or -O vector3 (Fortran) has been specified
on the compiler command line.
x
These functions evaluate y = e .
CF90
CDEXP is called implicitly by the Fortran 90 compiler as a result of a
generic EXP call with a complex double-precision argument.
CAL Register Usage (Cray Research Systems Only)
Scalar EXP: EXP% (call-by-register)
on entry (S1) = argument
on exit (S1) = result
Vector EXP: %EXP% (call-by-register)
on entry (V1) = argument vector
on exit (V1) = result vector
Scalar DEXP: DEXP% (call-by-register)
on entry (S1) and (S2) = argument
on exit (S1) and (S2) = result
Vector DEXP: %DEXP% (call-by-register)
on entry (V1) and (V2) = argument vector
on exit (V1) and (V2) = result vector
Scalar CEXP: CEXP% (call-by-register)
on entry (S1) and (S2) = argument
on exit (S1) and (S2) = result
Vector CEXP: %CEXP% (call-by-register)
on entry (V1) and (V2) = argument vector
on exit (V1) and (V2) = result vector
Scalar CDEXP: %CEDXP% (call-by-register)
on entry (S1), (S2), (S3), and (V4) = argument
on exit (S1), (S2), (S3), and (S4) = result
Vector CDEXP: %CEDXP% (call-by-register)
on entry (V1), (V2), (V3), and (V4) = argument vector
on exit (V1), (V2), (V3), and (V4) = result vector
Argument Range
EXP, DEXP:
13
|x| < 2 * ln 2
On UNICOS/mk systems and on CRAY T90 systems that support IEEE
arithmetic:
x > -708.3964 and x < 709.7827
CEXP:
13 13
|x| < 2 * ln 2 and |x | < 2 * ln 2
r
On UNICOS/mk systems and on CRAY T90 systems that support IEEE
arithmetic:
-708.3964 < x < 709.7827
r
25
|x | < 2
i
CDEXP:
13 45
|x | < 2 * ln 2, |x | < 2
r i
NOTESCDEXP is an outmoded routine for the CF90 compiler. Refer to the
Fortran Language Reference Manual, Volume 3, publication SR-3905, for
information about outmoded features and their preferred standard
alternatives.
The name of the EXP, DEXP, and CEXP intrinsic can be passed as an
argument. The name of the CDEXP intrinsic cannot be passed as an
argument.
RETURN VALUES x
EXP returns the real exponential function e of its real argument.
x
DEXP returns the double-precision exponential function e of its
double-precision argument.
x
CEXP returns the complex exponential function e of its complex
argument.
x
CDEXP returns the complex double exponential function e of its
complex double-precision argument.
On CRAY T90 systems that support IEEE arithmetic, the following return
values occur:
EXP(x) = 0 if x < -708.4
EXP(x) = infinity if x > 709.78
EXP(NaN) = NaN
SEE ALSO
Intrinsic Procedures Reference Manual, publication SR-2138, for the
printed version of this man page.
