#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.
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].
clog(z) = log(cabs(z)) + I * carg(z)
Note that z close to zero will cause an overflow.
These functions first appeared in glibc in version 2.1.
For an explanation of the terms used in this section, see attributes(7).
|clog(), clogf(), clogl()||Thread safety||MT-Safe|
C99, POSIX.1-2001, POSIX.1-2008.
cabs(3), cexp(3), clog10(3), clog2(3), complex(7)
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cacos(3), casin(3), catan(3), cexp(3), clog10(3), clog2(3), complex(7), log(3).
The man pages clogf(3) and clogl(3) are aliases of clog(3).