CLOG(3)                FreeBSD Library Functions Manual                CLOG(3)

NAME
     clog, clogf, and clogl - complex natural logarithm functions

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
     The clog(), clogf(), and clogl() functions compute the complex natural
     logarithm of z.  with a branch cut along the negative real axis .

RETURN VALUES
     The clog() function returns the complex natural logarithm value, in the
     range of a strip mathematically unbounded along the real axis and in the
     interval [-I* pi , +I* pi ] along the imaginary axis.  The function
     satisfies the relationship: clog(conj(z)) = conj(clog(z)).

     Argument                 Return value        Comment
     -0 + I*0                 -infinity + I*pi    Divide-by-zero exception
                                                  raised
     +0 + I*0                 -infinity + I*0     Divide by zero exception
                                                  raised
     x + I*infinity           +infinity + I*pi/2  For finite x
     x + I*NaN                NaN + I*NaN         Optionally raises invalid
                                                  floating-point exception
                                                  for finite x
     -infinity + I*y          +infinity + I*pi    For finite positive-signed y
     +infinity + I*y          +infinity + I*0     For finite positive-signed y
     -infinity + I*infinity   +infinity + I*3pi/4
     +infinity + I*infinity   +infinity + I*pi/4
     +-infinity + I*NaN       +infinity + I*NaN
     NaN + I*y                NaN + I*NaN         Optionally raises invalid
                                                  floating-point exception
                                                  for finite y
     NaN + I*infinity         +infinity + I*NaN
     NaN + I*NaN              NaN + I*NaN

SEE ALSO
     complex(3), log(3), math(3)

STANDARDS
     The clog(), cexpf(), and clogl() functions conform to ISO/IEC 9899:1999
     ("ISO C99").

FreeBSD 13.1-RELEASE-p6          June 6, 2018          FreeBSD 13.1-RELEASE-p6