---
title: clog
description: "计算复数以e为底数的对数值。"
url: https://www.hikunpeng.com/document/detail/zh/kunpengboostkithistory/240RC2/accel/kunpengaccel_kml_16_0570.html
sourcePath: /source/zh/kunpengboostkithistory/240RC2/accel/kunpengaccel_kml_16_0570.html
indexId: 7d5818a5a6c592397adef1ace0327aa548c6b2aebfbb0040cba7ee124194a88f76
---
# clog

计算复数以e为底数的对数值。

#### 接口定义

C interface：

float complex clogf(float complex x);

double complex clog(double complex x);

long double complex clogl(long double complex x);


#### 参数

| 参数名 | 类型 | 描述 | 输入/输出 |
| --- | --- | --- | --- |
| x | 在clogf中，x是复数单精度浮点类型。 在clog中，x是复数双精度浮点类型。 在clogl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的以e为底的对数值结果y。
- 特殊值说明如下所示。| 输入值实部（x.real） | 输入值虚部（x.imag） | 输出值实部（y.real） | 输出值虚部（y.imag） |
| --- | --- | --- | --- |
| +0 | +0 | \-inf | +0 |
| +0 | \-0 | \-inf | \-0 |
| +0 | inf | inf | pi/2 |
| +0 | \-inf | inf | \-pi/2 |
| +0 | snan | nan | nan |
| +0 | \-snan | nan | nan |
| +0 | qnan | nan | nan |
| +0 | \-qnan | nan | nan |
| \-0 | +0 | \-inf | pi |
| \-0 | \-0 | \-inf | \-pi |
| \-0 | inf | inf | pi/2 |
| \-0 | \-inf | inf | \-pi/2 |
| \-0 | snan | nan | nan |
| \-0 | \-snan | nan | nan |
| \-0 | qnan | nan | nan |
| \-0 | \-qnan | nan | nan |
| inf | +0 | inf | +0 |
| inf | \-0 | inf | \-0 |
| inf | inf | inf | pi/4 |
| inf | \-inf | inf | \-pi/4 |
| inf | snan | inf | nan |
| inf | \-snan | inf | nan |
| inf | qnan | inf | nan |
| inf | \-qnan | inf | nan |
| \-inf | +0 | inf | pi |
| \-inf | \-0 | inf | \-pi |
| \-inf | inf | inf | 3\*pi/4 |
| \-inf | \-inf | inf | \-3\*pi/4 |
| \-inf | snan | inf | nan |
| \-inf | \-snan | inf | nan |
| \-inf | qnan | inf | nan |
| \-inf | \-qnan | inf | nan |
| snan | +0 | nan | nan |
| snan | \-0 | nan | nan |
| snan | inf | inf | nan |
| snan | \-inf | inf | nan |
| snan | snan | nan | nan |
| snan | \-snan | nan | nan |
| snan | qnan | nan | nan |
| snan | \-qnan | nan | nan |
| \-snan | +0 | nan | nan |
| \-snan | \-0 | nan | nan |
| \-snan | inf | inf | nan |
| \-snan | \-inf | inf | nan |
| \-snan | snan | nan | nan |
| \-snan | \-snan | nan | nan |
| \-snan | qnan | nan | nan |
| \-snan | \-qnan | nan | nan |
| qnan | +0 | nan | nan |
| qnan | \-0 | nan | nan |
| qnan | inf | inf | nan |
| qnan | \-inf | inf | nan |
| qnan | snan | nan | nan |
| qnan | \-snan | nan | nan |
| qnan | qnan | nan | nan |
| qnan | \-qnan | nan | nan |
| \-qnan | +0 | nan | nan |
| \-qnan | \-0 | nan | nan |
| \-qnan | inf | inf | nan |
| \-qnan | \-inf | inf | nan |
| \-qnan | snan | nan | nan |
| \-qnan | \-snan | nan | nan |
| \-qnan | qnan | nan | nan |
| \-qnan | \-qnan | nan | nan |


#### 依赖

C: "kc.h"


#### 示例

C interface：
```
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;
double complex z1 = clog(__builtin_complex(x1, y1));
double complex z2 = clog(__builtin_complex(x2, y2));
double complex z3 = clog(__builtin_complex(x3, y3));
double complex z4 = clog(__builtin_complex(x4, y4));
double complex z5 = clog(__builtin_complex(x5, y5));
// print result
printf("/*\n");
printf(" * clog(%.2f + %.2f*I) = %.6f + %.6f*I\n", x1, y1, __real__(z1), __imag__(z1));
printf(" * clog(%.2f + %.2f*I) = %.6f + %.6f*I\n", x2, y2, __real__(z2), __imag__(z2));
printf(" * clog(%.2f + %.2f*I) = %.6f + %.6f*I\n", x3, y3, __real__(z3), __imag__(z3));
printf(" * clog(%.2f + %.2f*I) = %.6f + %.6f*I\n", x4, y4, __real__(z4), __imag__(z4));
printf(" * clog(%.2f + %.2f*I) = %.6f + %.6f*I\n", x5, y5, __real__(z5), __imag__(z5));
/*
* clog(inf + inf*I) = inf + 0.785398*I
* clog(2.00 + 3.00*I) = 1.282475 + 0.982794*I
* clog(-2.50 + -3.40*I) = 1.439880 + -2.204819*I
* clog(nan + nan*I) = nan + nan*I
* clog(0.00 + 0.00*I) = -inf + 0.000000*I
**/
```