lgamma_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 lgammaf_r(float x);
double lgamma_r(double x);
参数
参数名 |
类型 |
描述 |
输入/输出 |
|---|---|---|---|
x |
|
表示输入数据的浮点值。 |
输入 |
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=lgamma_r(0.0, &sign);
printf("lgamma_r(0.0, &sign) = %.15f, sign = %d\n", res, sign);
res=lgamma_r(-0.0, &sign);
printf("lgamma_r(-0.0, &sign) = %.15f, sign = %d\n", res, sign);
res=lgamma_r(0.25, &sign);
printf("lgamma_r(0.25, &sign) = %.15f, sign = %d\n", res, sign);
res=lgamma_r(-0.25, &sign);
printf("lgamma_r(-0.25, &sign) = %.15f, sign = %d\n", res, sign);
res=lgamma_r(0.5, &sign);
printf("lgamma_r(0.5, &sign) = %.15f, sign = %d\n", res, sign);
res=lgamma_r(-0.5, &sign);
printf("lgamma_r(-0.5, &sign) = %.15f, sign = %d\n", res, sign);
res=lgamma_r(1.0, &sign);
printf("lgamma_r(1.0, &sign) = %.15f, sign = %d\n", res, sign);
res=lgamma_r(-1.0, &sign);
printf("lgamma_r(-1.0, &sign) = %.15f, sign = %d\n", res, sign);
res=lgamma_r(2.0, &sign);
printf("lgamma_r(2.0, &sign) = %.15f, sign = %d\n", res, sign);
res=lgamma_r(-2.0, &sign);
printf("lgamma_r(-2.0, &sign) = %.15f, sign = %d\n", res, sign);
res=lgamma_r(INFINITY, &sign);
printf("lgamma_r(INFINITY, &sign) = %.15f, sign = %d\n", res, sign);
res=lgamma_r(-INFINITY, &sign);
printf("lgamma_r(-INFINITY, &sign) = %.15f, sign = %d\n", res, sign);
res=lgamma_r(NAN, &sign);
printf("lgamma_r(NAN, &sign) = %.15f, sign = %d\n", res, sign);
res=lgamma_r(-NAN, &sign);
printf("lgamma_r(-NAN, &sign) = %.15f, sign = %d\n", res, sign);
/*
* lgamma_r(0.0, &sign) = inf, sign = 1
* lgamma_r(-0.0, &sign) = inf, sign = -1
* lgamma_r(0.25, &sign) = 1.288022524698077, sign = 1
* lgamma_r(-0.25, &sign) = 1.589575312551186, sign = -1
* lgamma_r(0.5, &sign) = 0.572364942924700, sign = 1
* lgamma_r(-0.5, &sign) = 1.265512123484645, sign = -1
* lgamma_r(1.0, &sign) = 0.000000000000000, sign = 1
* lgamma_r(-1.0, &sign) = inf, sign = 1
* lgamma_r(2.0, &sign) = 0.000000000000000, sign = 1
* lgamma_r(-2.0, &sign) = inf, sign = 1
* lgamma_r(INFINITY, &sign) = inf, sign = 1
* lgamma_r(-INFINITY, &sign) = inf, sign = 1
* lgamma_r(NAN, &sign) = nan, sign = 1
* lgamma_r(-NAN, &sign) = -nan, sign = 1
*
* */
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