carg(3) - f39

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

6       carg, cargf, cargl - calculate the complex argument
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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 carg(double complex z);
15       float cargf(float complex z);
16       long double cargl(long double complex z);
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DESCRIPTION

19       These  functions  calculate the complex argument (also called phase an‐
20       gle) of z, with a branch cut along the negative real axis.
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22       A complex number can be described by two real coordinates.  One may use
23       rectangular coordinates and gets
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25           z = x + I * y
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27       where x = creal(z) and y = cimag(z).
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29       Or one may use polar coordinates and gets
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31           z = r * cexp(I * a)
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33       where r = cabs(z) is the "radius", the "modulus", the absolute value of
34       z, and a = carg(z) is the "phase angle", the argument of z.
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36       One has:
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38           tan(carg(z)) = cimag(z) / creal(z)
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RETURN VALUE

41       The return value is in the range of [-pi,pi].
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ATTRIBUTES

44       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
45       tributes(7).
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47       ┌────────────────────────────────────────────┬───────────────┬─────────┐
48       │Interface                                   │ Attribute     │ Value   │
49       ├────────────────────────────────────────────┼───────────────┼─────────┤
50       │carg(), cargf(), cargl()                    │ Thread safety │ MT-Safe │
51       └────────────────────────────────────────────┴───────────────┴─────────┘
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STANDARDS

54       C11, POSIX.1-2008.
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HISTORY

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