clog, clogf, clogl - natural logarithm of a complex number
Math library (
libm,
-lm)
#include <complex.h>
double complex clog(double complex z);
float complex clogf(float complex z);
long double complex clogl(long double complex z);
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.
These functions were added in glibc 2.1.
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
clog (), clogf (), clogl () |
Thread safety |
MT-Safe |
C99, POSIX.1-2001, POSIX.1-2008.
cabs(3),
cexp(3),
clog10(3),
clog2(3),
complex(7)