---
title: Gamma function
id: 5a23c84252665b21eecc7e76
challengeType: 5
videoUrl: ''
localeTitle: 伽玛功能
---
## Description
实现一个算法（或更多）来计算Gamma （$ \ Gamma $）函数（仅在实际字段中）。 Gamma功能可以定义为： $ \ Gamma（x）= \ displaystyle \ int_0 ^ \ infty t ^ {x-1} e ^ { - t} dt $
## Instructions
## Tests
```yml
tests:
- text: gamma应该是一个功能。
testString: 'assert(typeof gamma=="function","gamma should be a function.")'
- text: 'gamma("+tests[0]+")应该返回一个数字。'
testString: 'assert(typeof gamma(tests[0])=="number","gamma("+tests[0]+") should return a number.")'
- text: 'gamma("+tests[0]+")应该返回"+results[0]+" 。'
testString: 'assert.equal(gamma(tests[0]),results[0],"gamma("+tests[0]+") should return "+results[0]+".")'
- text: 'gamma("+tests[1]+")应该返回"+results[1]+" 。'
testString: 'assert.equal(gamma(tests[1]),results[1],"gamma("+tests[1]+") should return "+results[1]+".")'
- text: 'gamma("+tests[2]+")应该返回"+results[2]+" 。'
testString: 'assert.equal(gamma(tests[2]),results[2],"gamma("+tests[2]+") should return "+results[2]+".")'
- text: 'gamma("+tests[3]+")应该返回"+results[3]+" 。'
testString: 'assert.equal(gamma(tests[3]),results[3],"gamma("+tests[3]+") should return "+results[3]+".")'
- text: 'gamma("+tests[4]+")应返回"+results[4]+" 。'
testString: 'assert.equal(gamma(tests[4]),results[4],"gamma("+tests[4]+") should return "+results[4]+".")'
```
## Challenge Seed
```js
function gamma (x) {
// Good luck!
}
```
### After Test
```js
console.info('after the test');
```
## Solution
```js
// solution required
```