### NAME

clog, clogf, clogl - natural logarithm of a complex number

### SYNOPSIS

**#include <complex.h>**

**double complex clog(double complex ***z***);** **float complex clogf(float complex ***z***);** **long double complex clogl(long double complex ***z***);**

Link with *-lm*.

### DESCRIPTION

The logarithm
**clog**() is the inverse function of the exponential
cexp(3).
Thus, if *y = clog(z)*, then *z = cexp(y)*.
The imaginary part of
*y* is chosen in the interval [-pi,pi].

One has:

clog(z) = log(cabs(z)) + I * carg(z)

Note that
*z* close to zero will cause an overflow.

### VERSIONS

These functions first appeared in glibc in version 2.1.

### CONFORMING TO

C99.

### SEE ALSO

cabs(3), cexp(3), clog10(3), complex(7)

### COLOPHON

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