clog.3m (2010 09)

clog(3M) clog(3M)

(HP Integrity Server Only)

NAME

clog(), clogf(), clogl(), clogw(), clogq() - complex natural (base-e) logarithm functions

SYNOPSIS

#include <complex.h>

double complex clog(double complex z);

float complex clogf(float complex z);

long double complex clogl(long double complex z);

extended complex clogw(extended complex

z);

quad complex clogq(quad complex z);

DESCRIPTION

clog() returns the complex natural logarithm of z in the range of a strip mathematically unbounded

along the real axis and in the interval [-iPi,+iPi] along the imaginary axis. There is a branch cut along

the negative real axis.

clogf() is a float complex version of clog()

; it takes a float complex argument and returns a

float complex result.

clogl() is a long double complex version of clog(); it takes a long double complex argu-

ment and returns a long double complex result.

clogw() is an extended complex version of clog(); it takes an extended complex argument

and returns an extended complex result.

clogq() is equivalent to clogl() on HP-UX systems.

USAGE

To use these functions, compile with the default

-Ae option. To use clogw()

or clogq(), compile

with the

-fpwidetypes option. Make sure your program includes <complex.h>. Link in the math

library by specifying -lm on the compiler or linker command line.

RETURN VALUE

clog(conj(z)) = conj(clog(z)).

clog(-0+i0) returns -Inf+iPi and raises the divide-by-zero ﬂoating-point exception.

clog(+0+i0) returns -Inf+i0 and raises the divide-by-zero ﬂoating-point exception.

clog(x+iInf) returns +Inf+iPi/2, for ﬁnite x.

clog(x+iNaN) returns NaN+iNaN and optionally raises the invalid ﬂoating-point exception, for ﬁnite x.

clog(-Inf+iy) returns +Inf+iPi, for ﬁnite positive-signed y.

clog(+Inf+iy) returns +Inf+i0, for ﬁnite positive-signed y.

clog(-Inf+iInf) returns +Inf+i3Pi/4.

clog(+Inf+iInf) returns +Inf+iPi/4.

clog(±Inf+iNaN) returns +Inf+iNaN.

clog(NaN+iy) returns NaN+iNaN and optionally raises the invalid ﬂoating-point exception, for ﬁnite y.

clog(NaN+iInf) returns +Inf+iNaN.

clog(NaN+iNaN) returns NaN+iNaN.

ERRORS

No errors are deﬁned.