carg

cargf, carg, cargl

在头文件中定义
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）z用沿着负实轴的分支来计算参数（也称为相位角）。

4）式泛型宏：如果z具有类型long double complex，long double imaginary或long double，cargl被调用。如果z有类型float complex，float imaginary或者float，cargf被调用。如果z有类型double complex，double imaginary，double，或任何整数类型，carg被调用。

参数

z	-	复杂的论点

返回值

如果没有错误发生，则返回z间隔（-π;π）的相位角。

处理错误和特殊情况，就像该函数被实现为atan2(cimag(z), creal(z))。

例

#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)
}

输出：

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

参考

C11标准（ISO / IEC 9899：2011）：