---
title: carg
description: "返回复数极坐标形式的角度值。"
url: https://www.hikunpeng.com/document/detail/zh/kunpengboostkithistory/240RC1/accel/kunpengaccel_kml_16_0694.html
sourcePath: /source/zh/kunpengboostkithistory/240RC1/accel/kunpengaccel_kml_16_0694.html
indexId: 9194e5312ceb8cc444918a5776ea99330aebda756256f5d256354c2c7bd184e876
---
# carg

返回复数极坐标形式的角度值。

#### 接口定义

C interface：

float cargf(float complex x);

double carg(double complex x);

long double cargl(long double complex x);


#### 参数

| 参数名 | 类型 | 描述 | 输入/输出 |
| --- | --- | --- | --- |
| x | 在cargf中，x是复数单精度浮点类型。 在carg中，x是复数双精度浮点类型。 在cargl中，x是复数长双精度浮点类型。 | 表示输入数据的浮点值。 | 输入 |


#### 返回值

- 返回复数极坐标形式的角度值y，y ∈ [-pi, +pi]。
- 特殊值说明如下所示。| 输入值实部（real） | 输入值虚部（imag） | 输出值（y） |
| --- | --- | --- |
| +0 | +0 | +0 |
| +0 | \-0 | \-0 |
| +0 | inf | pi/2 |
| +0 | \-inf | \-pi/2 |
| +0 | snan | nan |
| +0 | \-snan | nan |
| +0 | qnan | nan |
| +0 | \-qnan | nan |
| \-0 | +0 | pi |
| \-0 | \-0 | \-pi |
| \-0 | inf | pi/2 |
| \-0 | \-inf | \-pi/2 |
| \-0 | snan | nan |
| \-0 | \-snan | nan |
| \-0 | qnan | nan |
| \-0 | \-qnan | nan |
| inf | +0 | +0 |
| inf | \-0 | \-0 |
| inf | inf | pi/4 |
| inf | \-inf | \-pi/4 |
| inf | snan | nan |
| inf | \-snan | nan |
| inf | qnan | nan |
| inf | \-qnan | nan |
| \-inf | +0 | pi |
| \-inf | \-0 | \-pi |
| \-inf | inf | 3\*pi/4 |
| \-inf | \-inf | \-3\*pi/4 |
| \-inf | snan | nan |
| \-inf | \-snan | nan |
| \-inf | qnan | nan |
| \-inf | \-qnan | nan |
| snan | +0 | nan |
| snan | \-0 | nan |
| snan | inf | nan |
| snan | \-inf | nan |
| snan | snan | nan |
| snan | \-snan | nan |
| snan | qnan | nan |
| snan | \-qnan | nan |
| \-snan | +0 | nan |
| \-snan | \-0 | nan |
| \-snan | inf | nan |
| \-snan | \-inf | nan |
| \-snan | snan | nan |
| \-snan | \-snan | nan |
| \-snan | qnan | nan |
| \-snan | \-qnan | nan |
| qnan | +0 | nan |
| qnan | \-0 | nan |
| qnan | inf | nan |
| qnan | \-inf | nan |
| qnan | snan | nan |
| qnan | \-snan | nan |
| qnan | qnan | nan |
| qnan | \-qnan | nan |
| \-qnan | +0 | nan |
| \-qnan | \-0 | nan |
| \-qnan | inf | nan |
| \-qnan | \-inf | nan |
| \-qnan | snan | nan |
| \-qnan | \-snan | nan |
| \-qnan | qnan | nan |
| \-qnan | \-qnan | nan |


#### 依赖

C: "km.h"


#### 示例

C interface：
```
// typical usage
double x1 = INFINITY, y1 = INFINITY;
double x2 = -INFINITY, y2 = 0;
double x3 = 0, y3 = -INFINITY;
double x4 = NAN, y4 = NAN;
double x5 = 0, y5 = 0;
// print result
printf("/*\n");
printf(" * carg(%.2f + %.2f*I) = %.6f\n", x1, y1, carg(__builtin_complex(x1, y1)));
printf(" * carg(%.2f + %.2f*I) = %.6f\n", x2, y2, carg(__builtin_complex(x2, y2)));
printf(" * carg(%.2f + %.2f*I) = %.6f\n", x3, y3, carg(__builtin_complex(x3, y3)));
printf(" * carg(%.2f + %.2f*I) = %.6f\n", x4, y4, carg(__builtin_complex(x4, y4)));
printf(" * carg(%.2f + %.2f*I) = %.6f\n", x5, y5, carg(__builtin_complex(x5, y5)));
/*
* carg(inf + inf*I) = 0.785398
* carg(-inf + 0.00*I) = 3.141593
* carg(0.00 + -inf*I) = -1.570796
* carg(nan + nan*I) = nan
* carg(0.00 + 0.00*I) = 0.000000
**/
```