---
title: cimag
description: "返回复数的虚部的值。"
url: https://www.hikunpeng.com/document/detail/zh/kunpenghpcs/hpckit/devg/kunpengaccel_kml_0281.html
sourcePath: /source/zh/kunpenghpcs/hpckit/devg/kunpengaccel_kml_0281.html
indexId: 721fd645bc1802fd5b35f80d9d15070f57f5908a11d8bba719c2a0eec78d84df61
---
# cimag

返回复数的虚部的值。

#### 接口定义

C interface：

float cimagf(float complex x);

double cimag(double complex x);

long double cimagl(long double complex x);


#### 参数

| 参数名 | 类型 | 描述 | 输入/输出 |
| --- | --- | --- | --- |
| x | 在cimagf中，x是复数单精度浮点类型。 在cimag中，x是复数双精度浮点类型。 在cimagl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x的虚部的值y，y ∈ (-INF, +INF)。


#### 依赖

C: "km.h"


#### 示例

C interface：```
// typical usage
    double x1 = INFINITY, y1 = INFINITY;
    double x2 = 2.0, y2 = 3.0;
    double x3 = -2.5, y3 = -3.4;
    double x4 = NAN, y4 = NAN;
    double x5 = 0, y5 = 0;
    // print result
    printf("/*\n");
    printf(" * cimag(%.2f + %.2f*I) = %.6f\n", x1, y1, cimag(__builtin_complex(x1, y1)));
    printf(" * cimag(%.2f + %.2f*I) = %.6f\n", x2, y2, cimag(__builtin_complex(x2, y2)));
    printf(" * cimag(%.2f + %.2f*I) = %.6f\n", x3, y3, cimag(__builtin_complex(x3, y3)));
    printf(" * cimag(%.2f + %.2f*I) = %.6f\n", x4, y4, cimag(__builtin_complex(x4, y4)));
    printf(" * cimag(%.2f + %.2f*I) = %.6f\n", x5, y5, cimag(__builtin_complex(x5, y5)));
    printf(" **/\n");
 
   /*
    * cimag(inf + inf*I) = inf
    * cimag(2.00 + 3.00*I) = 3.000000
    * cimag(-2.50 + -3.40*I) = -3.400000
    * cimag(nan + nan*I) = nan
    * cimag(0.00 + 0.00*I) = 0.000000
    **/
```