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Manual Pages  — CLOG

NAME

clog, clogf, and clogl – complex natural logarithm functions

CONTENTS

LIBRARY

Math Library (libm, -lm)

SYNOPSIS

#include <complex.h>

double complex
clog(double complex z);

float complex
clogf(float complex z);

long double complex
clogl(long double complex z);

DESCRIPTION

The clog(), clogf(), and clogl() functions compute the complex natural logarithm of z. with a branch cut along the negative real axis .

RETURN VALUES

The clog() function returns the complex natural logarithm value, in the range of a strip mathematically unbounded along the real axis and in the interval [-I* π , +I* π ] along the imaginary axis. The function satisfies the relationship: clog(conj(z)) = conj(clog(z)).

Argument Return value Comment

-0 + I*0
-∞ + I*π Divide-by-zero exception
raised

+0 + I*0
-∞ + I*0 Divide by zero exception
raised

x + I*∞
+∞ + I*π/2 For finite x

x + I*NaN
NaN + I*NaN Optionally raises invalid
floating-point exception
for finite x

-∞ + I*y
+∞ + I*π For finite positive-signed y

+∞ + I*y
+∞ + I*0 For finite positive-signed y

-∞ + I*∞
+∞ + I*3π/4

+∞ + I*∞
+∞ + I*π/4

&#177;∞ + I*NaN
+∞ + I*NaN

NaN + I*y
NaN + I*NaN Optionally raises invalid
floating-point exception
for finite y

NaN + I*∞
+∞ + I*NaN

NaN + I*NaN
NaN + I*NaN

SEE ALSO

complex(3), log(3), math(3)

STANDARDS

The clog(), cexpf(), and clogl() functions conform to ISO/IEC 9899:1999 ("ISO C99").

CLOG (3) June 6, 2018

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