Manpages - clog.3

clog, clogf, clogl - 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);

  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].

One has:

      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).

C99, POSIX.1-2001, POSIX.1-2008.

*cabs*(3), *cexp*(3), *clog10*(3), *clog2*(3), *complex*(7)

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