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manpages-dev_3.35-0.1ubuntu1_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__**);**
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), **clog2**(3), **complex**(7)

**COLOPHON**

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be found at http://man7.org/linux/man-pages/.
2008-08-11 CLOG(3)