clog(3) Library Functions Manual clog(3)
NAME
clog, clogf, clogl - natural logarithm of a complex number
LIBRARY
Math library (libm, -lm)
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.
ATTRIBUTES
For an explanation of the terms used in this section, see attrib-
utes(7).
┌───────────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├───────────────────────────────────────────┼───────────────┼─────────┤
│ clog(), clogf(), clogl() │ Thread safety │ MT-Safe │
└───────────────────────────────────────────┴───────────────┴─────────┘
STANDARDS
C11, POSIX.1-2008.
HISTORY
glibc 2.1. C99, POSIX.1-2001.
SEE ALSO
cabs(3), cexp(3), clog10(3), clog2(3), complex(7)
Linux man-pages 6.7 2023-10-31 clog(3)
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