

 
Manual Reference Pages  CEXPF (3)
NAME
cexp,
cexpf
 complex exponential functions
CONTENTS
Library
Synopsis
Description
Return Values
See Also
Standards
LIBRARY
.Lb libm
SYNOPSIS
.In complex.h
double complex
cexp double complex z
float complex
cexpf float complex z
DESCRIPTION
The
cexp
and
cexpf
functions compute the complex exponential of
z,
also known as
cis(
z).
RETURN VALUES
For real numbers
x
and
y,
cexp
behaves according to Euler’s formula:
cexp x + I*y
=
(e **
x *
cos(
y+())
I
*
e **
x
*
sin(
y))
Generally speaking, infinities, zeroes and NaNs are handled as would
be expected from this identity given the usual rules of floatingpoint
arithmetic.
However, care is taken to avoid generating NaNs when they are not deserved.
For example, mathematically we expect that
.Fo cimag
cexp x + I*0 Fc
= 0 regardless of the value of
x,
and
cexp
preserves this identity even if
x
is oo or NaN.
Likewise,
cexp oo + I*y
= 0 and
.Fo creal
cexp oo + I*y Fc
= oo
for any
y
(even though the latter property is only mathematically true for
representable
y.)
If
y
is not finite, the sign of the result is indeterminate.
SEE ALSO
complex(3),
exp(3),
math(3),
STANDARDS
The
cexp
and
cexpf
functions conform to
isoC99.
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