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Name

carg, cargf, cargl - calculate the complex argument

Library

Math library ( libm ", " -lm )

Synopsis

#include <complex.h> 
double carg(double complex " z ");
float cargf(float complex " z ");
long double cargl(long double complex " z ");

Description

These functions calculate the complex argument (also called phase angle) of z, with a branch cut along the negative real axis.

A complex number can be described by two real coordinates. One may use rectangular coordinates and gets

z = x + I * y

where x\~=\~creal(z) and y\~=\~cimag(z).

Or one may use polar coordinates and gets

z = r * cexp(I * a)

where r\~=\~cabs(z) is the "radius", the "modulus", the absolute value of z, and a\~=\~carg(z) is the "phase angle", the argument of z.

One has:

tan(carg(z)) = cimag(z) / creal(z)

Return Value

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

Attributes

For an explanation of the terms used in this section, see attributes(7). allbox; lbx lb lb T{ carg()cargf()cargl()
InterfaceAttributeValue
T}Thread safetyMT-Safe

Standards

C11, POSIX.1-2008.

History

glibc 2.1. C99, POSIX.1-2001.

See Also

  1. cabs(3),
  2. complex(7)