clog(3) — Linux manual page

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
       attributes(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)

COLOPHON

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Linux man-pages 6.9.1          2024-05-02                        clog(3)

Pages that refer to this page: cacos(3), casin(3), catan(3), cexp(3), clog10(3), clog2(3), log(3), complex(7)

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