clog
(3)natural logarithm of a complex number
#include <complex.h> double complex clog(double complex z); float complex clogf(float complex z); long double complex clogl(long double complex z);
LIBRARY
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.