| Defined in header <complex.h> | ||
|---|---|---|
float cargf( float complex z ); | (1) | (since C99) |
double carg( double complex z ); | (2) | (since C99) |
long double cargl( long double complex z ); | (3) | (since C99) |
| Defined in header <tgmath.h> | ||
#define carg( z ) | (4) | (since C99) |
1-3) Computes the argument (also called phase angle) of
z, with a branch cut along the negative real axis. 4) Type-generic macro: if
z has type long double complex, long double imaginary, or long double, cargl is called. If z has type float complex, float imaginary, or float, cargf is called. If z has type double complex, double imaginary, double, or any integer type, carg is called.Parameters
| z | - | complex argument |
Return value
If no errors occur, returns the phase angle of z in the interval (−π; π).
Errors and special cases are handled as if the function is implemented as atan2(cimag(z), creal(z)).
Example
#include <stdio.h>
#include <complex.h>
int main(void)
{
double complex z1 = 1.0+0.0*I;
printf("phase angle of %.1f%+.1fi is %f\n", creal(z1), cimag(z1), carg(z1));
double complex z2 = 0.0+1.0*I;
printf("phase angle of %.1f%+.1fi is %f\n", creal(z2), cimag(z2), carg(z2));
double complex z3 = -1.0+0.0*I;
printf("phase angle of %.1f%+.1fi is %f\n", creal(z3), cimag(z3), carg(z3));
double complex z4 = conj(z3); // or CMPLX(-1, -0.0)
printf("phase angle of %.1f%+.1fi (the other side of the cut) is %f\n",
creal(z4), cimag(z4), carg(z4));
}Output:
phase angle of 1.0+0.0i is 0.000000 phase angle of 0.0+1.0i is 1.570796 phase angle of -1.0+0.0i is 3.141593 phase angle of -1.0-0.0i (the other side of the cut) is -3.141593
References
- C11 standard (ISO/IEC 9899:2011):
- 7.3.9.1 The carg functions (p: 196)
- 7.25 Type-generic math <tgmath.h> (p: 373-375)
- G.7 Type-generic math <tgmath.h> (p: 545)
- C99 standard (ISO/IEC 9899:1999):
- 7.3.9.1 The carg functions (p: 178)
- 7.22 Type-generic math <tgmath.h> (p: 335-337)
- G.7 Type-generic math <tgmath.h> (p: 480)
See also
| (C99)(C99)(C99) | computes the magnitude of a complex number (function) |
| (C99)(C99) | computes arc tangent, using signs to determine quadrants (function) |
C++ documentation for arg | |
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