clog(3) - f39

1clog(3)                    Library Functions Manual                    clog(3)
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NAME

6       clog, clogf, clogl - natural logarithm of a complex number
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LIBRARY

9       Math library (libm, -lm)
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SYNOPSIS

12       #include <complex.h>
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14       double complex clog(double complex z);
15       float complex clogf(float complex z);
16       long double complex clogl(long double complex z);
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DESCRIPTION

19       These  functions  calculate  the complex natural logarithm of z, with a
20       branch cut along the negative real axis.
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22       The logarithm  clog()  is  the  inverse  function  of  the  exponential
23       cexp(3).   Thus,  if y = clog(z), then z = cexp(y).  The imaginary part
24       of y is chosen in the interval [-pi,pi].
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26       One has:
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28           clog(z) = log(cabs(z)) + I * carg(z)
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30       Note that z close to zero will cause an overflow.
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ATTRIBUTES

33       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
34       tributes(7).
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36       ┌────────────────────────────────────────────┬───────────────┬─────────┐
37       │Interface                                   │ Attribute     │ Value   │
38       ├────────────────────────────────────────────┼───────────────┼─────────┤
39       │clog(), clogf(), clogl()                    │ Thread safety │ MT-Safe │
40       └────────────────────────────────────────────┴───────────────┴─────────┘
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STANDARDS

43       C11, POSIX.1-2008.
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HISTORY

46       glibc 2.1.  C99, POSIX.1-2001.
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