# cargf, carg, cargl

< c‎ | numeric‎ | complex

C
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Complex number arithmetic
Types and the imaginary constant
 complex(C99) _Complex_I(C99) CMPLX(C11)
 imaginary(C99) _Imaginary_I(C99) I(C99)
Manipulation
 cimag(C99) creal(C99) carg(C99)
 cabs(C99) conj(C99) cproj(C99)
Power and exponential functions
 cexp(C99) clog(C99)
 cpow(C99) csqrt(C99)
Trigonometric functions
 ccos(C99) csin(C99) ctan(C99)
 cacos(C99) casin(C99) catan(C99)
Hyperbolic functions
 ccosh(C99) csinh(C99) ctanh(C99)
 cacosh(C99) casinh(C99) catanh(C99)

 Defined in header  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  #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.

## Contents

### 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)