Provided by: manpages-dev_4.15-1_all

#### 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);

```

#### DESCRIPTION

```       These  functions calculate the complex natural logarithm of z, with a branch cut along the
negative real axis.

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.

```

#### ATTRIBUTES

```       For an explanation of the terms used in this section, see attributes(7).

┌─────────────────────────┬───────────────┬─────────┐
│Interface                │ Attribute     │ Value   │
├─────────────────────────┼───────────────┼─────────┤
│clog(), clogf(), clogl() │ Thread safety │ MT-Safe │
└─────────────────────────┴───────────────┴─────────┘
```

#### CONFORMINGTO

```       C99, POSIX.1-2001, POSIX.1-2008.

```

#### SEEALSO

```       cabs(3), cexp(3), clog10(3), clog2(3), complex(7)

```

#### COLOPHON

```       This page is part of release 4.15 of the Linux man-pages project.  A  description  of  the