---
title: tanpi
description: "计算输入实数与π相乘的正切值。"
url: https://www.hikunpeng.com/document/detail/zh/kunpenghpcs/hpckit/devg/kunpengaccel_kml_0161.html
sourcePath: /source/zh/kunpenghpcs/hpckit/devg/kunpengaccel_kml_0161.html
indexId: e2c8ad67bd1aa4ad8908ab81013bf797ed03d787e91ed63fa7981be634a1aeaa61
---
# tanpi

计算输入实数与π相乘的正切值。

#### 接口定义

C interface：

float tanpif(float x);

double tanpi(double x);


#### 参数

| 参数名 | 类型 | 描述 | 输入/输出 |
| --- | --- | --- | --- |
| x | 在tanpif中，x是单精度浮点类型。 在tanpi中，x是双精度浮点类型。 | 表示输入数据的浮点值。 | 输入 |


#### 返回值

- 返回x乘以π的正切函数值y=tan(x * π)。
- 输入+0，返回+0。
- 输入-0，返回-0。
- 输入±∞，返回nan。
- 输入nan，返回nan。


#### 依赖

C: "km.h"


#### 示例

C interface：

```
// typical usage
float x1 = -0.2, x2 = 0.2, x3 = 0.4, x4 = -0.4;
// special handling
float a = 0.0, b = INFINITY, c = -INFINITY, d = NAN;
// print result
printf("tanpi(0.2) = %.15f\n", tanpi(x1));
printf("tanpi(-0.2) = %.15f\n", tanpi(x2));
printf("tanpi(0.4) = %.15f\n", tanpi(x3));
printf("tanpi(-0.4) = %.15f\n", tanpi(x4));
printf("tanpi(0.0) = %.15f\n", tanpi(a));
printf("tanpi(-0.0) = %.15f\n", tanpi(-a));
printf("tanpi(INFINITY) = %.15f\n", tanpi(b));
printf("tanpi(-INFINITY) = %.15f\n", tanpi(c));
printf("tanpi(NAN) = %.15f\n", tanpi(d));
/*
 * tanpi(0.2) = -0.726542542310257
 * tanpi(-0.2) = 0.726542542310257
 * tanpi(0.4) = 3.077683733269691
 * tanpi(-0.4) = -3.077683733269691
 * tanpi(0.0) = 0.000000000000000
 * tanpi(-0.0) = -0.000000000000000
 * tanpi(INFINITY) = nan 
 * tanpi(-INFINITY) = nan
 * tanpi(NAN) = nan
 * */
```