---
title: gamma_r
description: "计算x的伽马值绝对值的自然对数，返回伽马值的符号，输入参数为实数。"
url: https://www.hikunpeng.com/document/detail/zh/hpchistory/hpckit/develop2400/kunpengaccel_kml_0222.html
sourcePath: /source/zh/hpchistory/hpckit/develop2400/kunpengaccel_kml_0222.html
indexId: 77ee44d72481e4edd35ce39fd3bf64ea78ea0167b76d22f7784a6836d36c19fa67
---
# gamma_r

计算x的伽马值绝对值的自然对数，返回伽马值的符号，输入参数为实数。

#### 接口定义

C interface：

float gammaf_r(float x, int *signgam);

double gamma_r(double x, int *signgam);


#### 参数

| 参数名 | 类型 | 描述 | 输入/输出 |
| --- | --- | --- | --- |
| x | 在gammaf\_r中，x是单精度浮点类型。 在gamma\_r中，x是双精度浮点类型。 | 表示输入数据的浮点值。 | 输入 |
| signgam | 在gammaf\_r中，signgam是整数类型指针。 在gamma\_r中，signgam是整数类型指针。 | 存储x的伽马值的符号 | 输出 |


#### 返回值

- 返回入参x的伽马值绝对值的自然对数、伽马值的符号。
- 输入nan，返回nan，符号为1。
- 输入+∞，返回+∞，符号为1。
- 输入-∞，返回+∞，符号为1。
- 输入+0，返回+∞，符号为1。
- 输入-0，返回+∞，符号为-1。


#### 依赖

C: "km.h"


#### 示例

C interface：
```
// print result
int sign=0;
double res=0.0;
res=gamma_r(0.0, &sign);
printf("gamma_r(0.0, &sign) = %.15f, sign = %d\n", res, sign);
res=gamma_r(-0.0, &sign);
printf("gamma_r(-0.0, &sign) = %.15f, sign = %d\n", res, sign);
res=gamma_r(0.25, &sign);
printf("gamma_r(0.25, &sign) = %.15f, sign = %d\n", res, sign);
res=gamma_r(-0.25, &sign);
printf("gamma_r(-0.25, &sign) = %.15f, sign = %d\n", res, sign);
res=gamma_r(0.5, &sign);
printf("gamma_r(0.5, &sign) = %.15f, sign = %d\n", res, sign);
res=gamma_r(-0.5, &sign);
printf("gamma_r(-0.5, &sign) = %.15f, sign = %d\n", res, sign);
res=gamma_r(1.0, &sign);
printf("gamma_r(1.0, &sign) = %.15f, sign = %d\n", res, sign);
res=gamma_r(-1.0, &sign);
printf("gamma_r(-1.0, &sign) = %.15f, sign = %d\n", res, sign);
res=gamma_r(2.0, &sign);
printf("gamma_r(2.0, &sign) = %.15f, sign = %d\n", res, sign);
res=gamma_r(-2.0, &sign);
printf("gamma_r(-2.0, &sign) = %.15f, sign = %d\n", res, sign);
res=gamma_r(INFINITY, &sign);
printf("gamma_r(INFINITY, &sign) = %.15f, sign = %d\n", res, sign);
res=gamma_r(-INFINITY, &sign);
printf("gamma_r(-INFINITY, &sign) = %.15f, sign = %d\n", res, sign);
res=gamma_r(NAN, &sign);
printf("gamma_r(NAN, &sign) = %.15f, sign = %d\n", res, sign);
res=gamma_r(-NAN, &sign);
printf("gamma_r(-NAN, &sign) = %.15f, sign = %d\n", res, sign);
/*
* gamma_r(0.0, &sign) = inf, sign = 1
* gamma_r(-0.0, &sign) = inf, sign = -1
* gamma_r(0.25, &sign) = 1.288022524698077, sign = 1
* gamma_r(-0.25, &sign) = 1.589575312551186, sign = -1
* gamma_r(0.5, &sign) = 0.572364942924700, sign = 1
* gamma_r(-0.5, &sign) = 1.265512123484645, sign = -1
* gamma_r(1.0, &sign) = 0.000000000000000, sign = 1
* gamma_r(-1.0, &sign) = inf, sign = 1
* gamma_r(2.0, &sign) = 0.000000000000000, sign = 1
* gamma_r(-2.0, &sign) = inf, sign = 1
* gamma_r(INFINITY, &sign) = inf, sign = 1
* gamma_r(-INFINITY, &sign) = inf, sign = 1
* gamma_r(NAN, &sign) = nan, sign = 1
* gamma_r(-NAN, &sign) = -nan, sign = 1
*
* */
```