---
title: cosd
description: "计算输入角度的余弦值。"
url: https://www.hikunpeng.com/document/detail/zh/kunpengboostkithistory/2300/accel/kunpengaccel_kml_16_0360.html
sourcePath: /source/zh/kunpengboostkithistory/2300/accel/kunpengaccel_kml_16_0360.html
indexId: fb047ebb49e04d635495a0ebb0f98de9f146cf655d44425b0451e8fd45b90b2f74
---
# cosd

计算输入角度的余弦值。

#### 接口定义

C interface：

float cosdf(float x);

double cosd(double x);

double cosd_18(double x);

long double cosdl(long double);

cosd_18仅在高精度版本提供。


#### 参数

| 参数名 | 类型 | 描述 | 输入/输出 |
| --- | --- | --- | --- |
| x | 在cosdf中，x是单精度浮点类型。 在cosd和cosd\_18中，x是双精度浮点类型。 在cosdl中，x是长双精度浮点类型。 | 表示角度的浮点值。 | 输入 |


#### 返回值

- 返回角度x的余弦函数值y，y ∈ [-1, +1]。
- 输入+0，返回1。
- 输入-0，返回1。
- 输入±∞，返回nan。
- 输入±nan，返回±nan。


#### 依赖

C: "km.h"


#### 示例

C interface：
```
// typical usage
float x1 = 90.0, x2 = -90.0, x3 = 45.0, x4 = -45.0, x5 = 30.0, x6 = -30.0;
float a = 0.0, b = INFINITY, c = -INFINITY, d = NAN;
// print result
printf("cosd(90.0) = %.15f\n", cosd(x1));
printf("cosd(-90.0) = %.15f\n", cosd(x2));
printf("cosd(45.0) = %.15f\n", cosd(x3));
printf("cosd(-45.0) = %.15f\n", cosd(x4));
printf("cosd(30.0) = %.15f\n", cosd(x5));
printf("cosd(-30.0) = %.15f\n", cosd(x6));
printf("cosd(0.0) = %.15f\n", cosd(a));
printf("cosd(-0.0) = %.15f\n", cosd(-a));
printf("cosd(INFINITY) = %.15f\n", cosd(b));
printf("cosd(-INFINITY) = %.15f\n", cosd(c));
printf("cosd(NAN) = %.15f\n", cosd(d));
/*
* cosd(90.0) = 0.000000000000000
* cosd(-90.0) = 0.000000000000000
* cosd(45.0) = 0.707106781186548
* cosd(-45.0) = 0.707106781186548
* cosd(30.0) = 0.866025403784439
* cosd(-30.0) = 0.866025403784439
* cosd(0.0) = 1.000000000000000
* cosd(-0.0) = 1.000000000000000
* cosd(INFINITY) = nan
* cosd(-INFINITY) = nan
* cosd(NAN) = nan
*
* */
```