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<title>浮點數 | Go语言圣经</title>
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<div class="book"
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data-chapter-title="浮點數"
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前言
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<li class="chapter " data-level="0.1" data-path="ch0/ch0-01.html">
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<b>0.1.</b>
Go語言起源
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<b>0.2.</b>
Go語言項目
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<b>0.3.</b>
本書的組織
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<b>0.4.</b>
更多的信息
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<b>0.5.</b>
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致謝
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</a>
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</ul>
</li>
<li class="chapter " data-level="1" data-path="ch1/ch1.html">
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<b>1.</b>
入門
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<li class="chapter " data-level="1.1" data-path="ch1/ch1-01.html">
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<b>1.1.</b>
Hello, World
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<b>1.2.</b>
命令行參數
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<a href="../ch1/ch1-03.html">
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<b>1.3.</b>
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査找重複的行
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</a>
</li>
<li class="chapter " data-level="1.4" data-path="ch1/ch1-04.html">
<a href="../ch1/ch1-04.html">
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<b>1.4.</b>
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GIF動畵
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</a>
</li>
<li class="chapter " data-level="1.5" data-path="ch1/ch1-05.html">
<a href="../ch1/ch1-05.html">
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<b>1.5.</b>
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獲取URL
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</a>
</li>
<li class="chapter " data-level="1.6" data-path="ch1/ch1-06.html">
<a href="../ch1/ch1-06.html">
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<b>1.6.</b>
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併發獲取多個URL
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</a>
</li>
<li class="chapter " data-level="1.7" data-path="ch1/ch1-07.html">
<a href="../ch1/ch1-07.html">
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<b>1.7.</b>
Web服務
</a>
</li>
<li class="chapter " data-level="1.8" data-path="ch1/ch1-08.html">
<a href="../ch1/ch1-08.html">
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<b>1.8.</b>
本章要點
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</ul>
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<li class="chapter " data-level="2" data-path="ch2/ch2.html">
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<b>2.</b>
程序結構
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<li class="chapter " data-level="2.1" data-path="ch2/ch2-01.html">
<a href="../ch2/ch2-01.html">
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<b>2.1.</b>
命名
</a>
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<li class="chapter " data-level="2.2" data-path="ch2/ch2-02.html">
<a href="../ch2/ch2-02.html">
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<b>2.2.</b>
聲明
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<li class="chapter " data-level="2.3" data-path="ch2/ch2-03.html">
<a href="../ch2/ch2-03.html">
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<b>2.3.</b>
變量
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<li class="chapter " data-level="2.4" data-path="ch2/ch2-04.html">
<a href="../ch2/ch2-04.html">
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<b>2.4.</b>
賦值
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<a href="../ch2/ch2-05.html">
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<b>2.5.</b>
類型
</a>
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<a href="../ch2/ch2-06.html">
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<b>2.6.</b>
包和文件
</a>
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<li class="chapter " data-level="2.7" data-path="ch2/ch2-07.html">
<a href="../ch2/ch2-07.html">
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<b>2.7.</b>
作用域
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="3" data-path="ch3/ch3.html">
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<b>3.</b>
基礎數據類型
</a>
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<li class="chapter " data-level="3.1" data-path="ch3/ch3-01.html">
<a href="../ch3/ch3-01.html">
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<b>3.1.</b>
整型
</a>
</li>
<li class="chapter active" data-level="3.2" data-path="ch3/ch3-02.html">
<a href="../ch3/ch3-02.html">
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<b>3.2.</b>
浮點數
</a>
</li>
<li class="chapter " data-level="3.3" data-path="ch3/ch3-03.html">
<a href="../ch3/ch3-03.html">
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<b>3.3.</b>
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複數
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</a>
</li>
<li class="chapter " data-level="3.4" data-path="ch3/ch3-04.html">
<a href="../ch3/ch3-04.html">
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<b>3.4.</b>
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布爾型
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</a>
</li>
<li class="chapter " data-level="3.5" data-path="ch3/ch3-05.html">
<a href="../ch3/ch3-05.html">
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<b>3.5.</b>
字符串
</a>
</li>
<li class="chapter " data-level="3.6" data-path="ch3/ch3-06.html">
<a href="../ch3/ch3-06.html">
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<b>3.6.</b>
常量
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="4" data-path="ch4/ch4.html">
<a href="../ch4/ch4.html">
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<b>4.</b>
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複合數據類型
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</a>
<ul class="articles">
<li class="chapter " data-level="4.1" data-path="ch4/ch4-01.html">
<a href="../ch4/ch4-01.html">
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<b>4.1.</b>
數組
</a>
</li>
<li class="chapter " data-level="4.2" data-path="ch4/ch4-02.html">
<a href="../ch4/ch4-02.html">
<i class="fa fa-check"></i>
<b>4.2.</b>
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Slice
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</a>
</li>
<li class="chapter " data-level="4.3" data-path="ch4/ch4-03.html">
<a href="../ch4/ch4-03.html">
<i class="fa fa-check"></i>
<b>4.3.</b>
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Map
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</a>
</li>
<li class="chapter " data-level="4.4" data-path="ch4/ch4-04.html">
<a href="../ch4/ch4-04.html">
<i class="fa fa-check"></i>
<b>4.4.</b>
結構體
</a>
</li>
<li class="chapter " data-level="4.5" data-path="ch4/ch4-05.html">
<a href="../ch4/ch4-05.html">
<i class="fa fa-check"></i>
<b>4.5.</b>
JSON
</a>
</li>
<li class="chapter " data-level="4.6" data-path="ch4/ch4-06.html">
<a href="../ch4/ch4-06.html">
<i class="fa fa-check"></i>
<b>4.6.</b>
文本和HTML模闆
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="5" data-path="ch5/ch5.html">
<a href="../ch5/ch5.html">
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<b>5.</b>
函數
</a>
<ul class="articles">
<li class="chapter " data-level="5.1" data-path="ch5/ch5-01.html">
<a href="../ch5/ch5-01.html">
<i class="fa fa-check"></i>
<b>5.1.</b>
函數聲明
</a>
</li>
<li class="chapter " data-level="5.2" data-path="ch5/ch5-02.html">
<a href="../ch5/ch5-02.html">
<i class="fa fa-check"></i>
<b>5.2.</b>
遞歸
</a>
</li>
<li class="chapter " data-level="5.3" data-path="ch5/ch5-03.html">
<a href="../ch5/ch5-03.html">
<i class="fa fa-check"></i>
<b>5.3.</b>
多返迴值
</a>
</li>
<li class="chapter " data-level="5.4" data-path="ch5/ch5-04.html">
<a href="../ch5/ch5-04.html">
<i class="fa fa-check"></i>
<b>5.4.</b>
錯誤
</a>
</li>
<li class="chapter " data-level="5.5" data-path="ch5/ch5-05.html">
<a href="../ch5/ch5-05.html">
<i class="fa fa-check"></i>
<b>5.5.</b>
函數值
</a>
</li>
<li class="chapter " data-level="5.6" data-path="ch5/ch5-06.html">
<a href="../ch5/ch5-06.html">
<i class="fa fa-check"></i>
<b>5.6.</b>
匿名函數
</a>
</li>
<li class="chapter " data-level="5.7" data-path="ch5/ch5-07.html">
<a href="../ch5/ch5-07.html">
<i class="fa fa-check"></i>
<b>5.7.</b>
可變參數
</a>
</li>
<li class="chapter " data-level="5.8" data-path="ch5/ch5-08.html">
<a href="../ch5/ch5-08.html">
<i class="fa fa-check"></i>
<b>5.8.</b>
Deferred函數
</a>
</li>
<li class="chapter " data-level="5.9" data-path="ch5/ch5-09.html">
<a href="../ch5/ch5-09.html">
<i class="fa fa-check"></i>
<b>5.9.</b>
Panic異常
</a>
</li>
<li class="chapter " data-level="5.10" data-path="ch5/ch5-10.html">
<a href="../ch5/ch5-10.html">
<i class="fa fa-check"></i>
<b>5.10.</b>
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Recover捕獲異常
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</a>
</li>
</ul>
</li>
<li class="chapter " data-level="6" data-path="ch6/ch6.html">
<a href="../ch6/ch6.html">
<i class="fa fa-check"></i>
<b>6.</b>
方法
</a>
<ul class="articles">
<li class="chapter " data-level="6.1" data-path="ch6/ch6-01.html">
<a href="../ch6/ch6-01.html">
<i class="fa fa-check"></i>
<b>6.1.</b>
方法聲明
</a>
</li>
<li class="chapter " data-level="6.2" data-path="ch6/ch6-02.html">
<a href="../ch6/ch6-02.html">
<i class="fa fa-check"></i>
<b>6.2.</b>
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基於指針對象的方法
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</a>
</li>
<li class="chapter " data-level="6.3" data-path="ch6/ch6-03.html">
<a href="../ch6/ch6-03.html">
<i class="fa fa-check"></i>
<b>6.3.</b>
通過嵌入結構體來擴展類型
</a>
</li>
<li class="chapter " data-level="6.4" data-path="ch6/ch6-04.html">
<a href="../ch6/ch6-04.html">
<i class="fa fa-check"></i>
<b>6.4.</b>
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方法值和方法表達式
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</a>
</li>
<li class="chapter " data-level="6.5" data-path="ch6/ch6-05.html">
<a href="../ch6/ch6-05.html">
<i class="fa fa-check"></i>
<b>6.5.</b>
示例: Bit數組
</a>
</li>
<li class="chapter " data-level="6.6" data-path="ch6/ch6-06.html">
<a href="../ch6/ch6-06.html">
<i class="fa fa-check"></i>
<b>6.6.</b>
封裝
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="7" data-path="ch7/ch7.html">
<a href="../ch7/ch7.html">
<i class="fa fa-check"></i>
<b>7.</b>
接口
</a>
<ul class="articles">
<li class="chapter " data-level="7.1" data-path="ch7/ch7-01.html">
<a href="../ch7/ch7-01.html">
<i class="fa fa-check"></i>
<b>7.1.</b>
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接口是合約
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</a>
</li>
<li class="chapter " data-level="7.2" data-path="ch7/ch7-02.html">
<a href="../ch7/ch7-02.html">
<i class="fa fa-check"></i>
<b>7.2.</b>
接口類型
</a>
</li>
<li class="chapter " data-level="7.3" data-path="ch7/ch7-03.html">
<a href="../ch7/ch7-03.html">
<i class="fa fa-check"></i>
<b>7.3.</b>
實現接口的條件
</a>
</li>
<li class="chapter " data-level="7.4" data-path="ch7/ch7-04.html">
<a href="../ch7/ch7-04.html">
<i class="fa fa-check"></i>
<b>7.4.</b>
flag.Value接口
</a>
</li>
<li class="chapter " data-level="7.5" data-path="ch7/ch7-05.html">
<a href="../ch7/ch7-05.html">
<i class="fa fa-check"></i>
<b>7.5.</b>
接口值
</a>
</li>
<li class="chapter " data-level="7.6" data-path="ch7/ch7-06.html">
<a href="../ch7/ch7-06.html">
<i class="fa fa-check"></i>
<b>7.6.</b>
sort.Interface接口
</a>
</li>
<li class="chapter " data-level="7.7" data-path="ch7/ch7-07.html">
<a href="../ch7/ch7-07.html">
<i class="fa fa-check"></i>
<b>7.7.</b>
http.Handler接口
</a>
</li>
<li class="chapter " data-level="7.8" data-path="ch7/ch7-08.html">
<a href="../ch7/ch7-08.html">
<i class="fa fa-check"></i>
<b>7.8.</b>
error接口
</a>
</li>
<li class="chapter " data-level="7.9" data-path="ch7/ch7-09.html">
<a href="../ch7/ch7-09.html">
<i class="fa fa-check"></i>
<b>7.9.</b>
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示例: 表達式求值
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</a>
</li>
<li class="chapter " data-level="7.10" data-path="ch7/ch7-10.html">
<a href="../ch7/ch7-10.html">
<i class="fa fa-check"></i>
<b>7.10.</b>
類型斷言
</a>
</li>
<li class="chapter " data-level="7.11" data-path="ch7/ch7-11.html">
<a href="../ch7/ch7-11.html">
<i class="fa fa-check"></i>
<b>7.11.</b>
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基於類型斷言識别錯誤類型
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</a>
</li>
<li class="chapter " data-level="7.12" data-path="ch7/ch7-12.html">
<a href="../ch7/ch7-12.html">
<i class="fa fa-check"></i>
<b>7.12.</b>
通過類型斷言査詢接口
</a>
</li>
<li class="chapter " data-level="7.13" data-path="ch7/ch7-13.html">
<a href="../ch7/ch7-13.html">
<i class="fa fa-check"></i>
<b>7.13.</b>
類型分支
</a>
</li>
<li class="chapter " data-level="7.14" data-path="ch7/ch7-14.html">
<a href="../ch7/ch7-14.html">
<i class="fa fa-check"></i>
<b>7.14.</b>
示例: 基於標記的XML解碼
</a>
</li>
<li class="chapter " data-level="7.15" data-path="ch7/ch7-15.html">
<a href="../ch7/ch7-15.html">
<i class="fa fa-check"></i>
<b>7.15.</b>
補充幾點
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="8" data-path="ch8/ch8.html">
<a href="../ch8/ch8.html">
<i class="fa fa-check"></i>
<b>8.</b>
Goroutines和Channels
</a>
<ul class="articles">
<li class="chapter " data-level="8.1" data-path="ch8/ch8-01.html">
<a href="../ch8/ch8-01.html">
<i class="fa fa-check"></i>
<b>8.1.</b>
Goroutines
</a>
</li>
<li class="chapter " data-level="8.2" data-path="ch8/ch8-02.html">
<a href="../ch8/ch8-02.html">
<i class="fa fa-check"></i>
<b>8.2.</b>
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示例: 併發的Clock服務
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</a>
</li>
<li class="chapter " data-level="8.3" data-path="ch8/ch8-03.html">
<a href="../ch8/ch8-03.html">
<i class="fa fa-check"></i>
<b>8.3.</b>
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示例: 併發的Echo服務
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</a>
</li>
<li class="chapter " data-level="8.4" data-path="ch8/ch8-04.html">
<a href="../ch8/ch8-04.html">
<i class="fa fa-check"></i>
<b>8.4.</b>
Channels
</a>
</li>
<li class="chapter " data-level="8.5" data-path="ch8/ch8-05.html">
<a href="../ch8/ch8-05.html">
<i class="fa fa-check"></i>
<b>8.5.</b>
併行的循環
</a>
</li>
<li class="chapter " data-level="8.6" data-path="ch8/ch8-06.html">
<a href="../ch8/ch8-06.html">
<i class="fa fa-check"></i>
<b>8.6.</b>
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示例: 併發的Web爬蟲
2015-12-09 07:57:17 +00:00
</a>
</li>
<li class="chapter " data-level="8.7" data-path="ch8/ch8-07.html">
<a href="../ch8/ch8-07.html">
<i class="fa fa-check"></i>
<b>8.7.</b>
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基於select的多路複用
2015-12-09 07:57:17 +00:00
</a>
</li>
<li class="chapter " data-level="8.8" data-path="ch8/ch8-08.html">
<a href="../ch8/ch8-08.html">
<i class="fa fa-check"></i>
<b>8.8.</b>
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示例: 併發的字典遍歷
2015-12-09 07:57:17 +00:00
</a>
</li>
<li class="chapter " data-level="8.9" data-path="ch8/ch8-09.html">
<a href="../ch8/ch8-09.html">
<i class="fa fa-check"></i>
<b>8.9.</b>
2015-12-28 08:08:26 +00:00
併發的退出
2015-12-09 07:57:17 +00:00
</a>
</li>
<li class="chapter " data-level="8.10" data-path="ch8/ch8-10.html">
<a href="../ch8/ch8-10.html">
<i class="fa fa-check"></i>
<b>8.10.</b>
示例: 聊天服務
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="9" data-path="ch9/ch9.html">
<a href="../ch9/ch9.html">
<i class="fa fa-check"></i>
<b>9.</b>
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基於共享變量的併發
2015-12-09 07:57:17 +00:00
</a>
<ul class="articles">
<li class="chapter " data-level="9.1" data-path="ch9/ch9-01.html">
<a href="../ch9/ch9-01.html">
<i class="fa fa-check"></i>
<b>9.1.</b>
競爭條件
</a>
</li>
<li class="chapter " data-level="9.2" data-path="ch9/ch9-02.html">
<a href="../ch9/ch9-02.html">
<i class="fa fa-check"></i>
<b>9.2.</b>
sync.Mutex互斥鎖
</a>
</li>
<li class="chapter " data-level="9.3" data-path="ch9/ch9-03.html">
<a href="../ch9/ch9-03.html">
<i class="fa fa-check"></i>
<b>9.3.</b>
sync.RWMutex讀寫鎖
</a>
</li>
<li class="chapter " data-level="9.4" data-path="ch9/ch9-04.html">
<a href="../ch9/ch9-04.html">
<i class="fa fa-check"></i>
<b>9.4.</b>
2015-12-21 04:55:18 +00:00
內存同步
2015-12-09 07:57:17 +00:00
</a>
</li>
<li class="chapter " data-level="9.5" data-path="ch9/ch9-05.html">
<a href="../ch9/ch9-05.html">
<i class="fa fa-check"></i>
<b>9.5.</b>
sync.Once初始化
</a>
</li>
<li class="chapter " data-level="9.6" data-path="ch9/ch9-06.html">
<a href="../ch9/ch9-06.html">
<i class="fa fa-check"></i>
<b>9.6.</b>
競爭條件檢測
</a>
</li>
<li class="chapter " data-level="9.7" data-path="ch9/ch9-07.html">
<a href="../ch9/ch9-07.html">
<i class="fa fa-check"></i>
<b>9.7.</b>
2015-12-21 04:55:18 +00:00
示例: 併發的非阻塞緩存
2015-12-09 07:57:17 +00:00
</a>
</li>
<li class="chapter " data-level="9.8" data-path="ch9/ch9-08.html">
<a href="../ch9/ch9-08.html">
<i class="fa fa-check"></i>
<b>9.8.</b>
2015-12-21 04:55:18 +00:00
Goroutines和線程
2015-12-09 07:57:17 +00:00
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="10" data-path="ch10/ch10.html">
<a href="../ch10/ch10.html">
<i class="fa fa-check"></i>
<b>10.</b>
包和工具
</a>
<ul class="articles">
<li class="chapter " data-level="10.1" data-path="ch10/ch10-01.html">
<a href="../ch10/ch10-01.html">
<i class="fa fa-check"></i>
<b>10.1.</b>
簡介
</a>
</li>
<li class="chapter " data-level="10.2" data-path="ch10/ch10-02.html">
<a href="../ch10/ch10-02.html">
<i class="fa fa-check"></i>
<b>10.2.</b>
導入路徑
</a>
</li>
<li class="chapter " data-level="10.3" data-path="ch10/ch10-03.html">
<a href="../ch10/ch10-03.html">
<i class="fa fa-check"></i>
<b>10.3.</b>
包聲明
</a>
</li>
<li class="chapter " data-level="10.4" data-path="ch10/ch10-04.html">
<a href="../ch10/ch10-04.html">
<i class="fa fa-check"></i>
<b>10.4.</b>
導入聲明
</a>
</li>
<li class="chapter " data-level="10.5" data-path="ch10/ch10-05.html">
<a href="../ch10/ch10-05.html">
<i class="fa fa-check"></i>
<b>10.5.</b>
匿名導入
</a>
</li>
<li class="chapter " data-level="10.6" data-path="ch10/ch10-06.html">
<a href="../ch10/ch10-06.html">
<i class="fa fa-check"></i>
<b>10.6.</b>
包和命名
</a>
</li>
<li class="chapter " data-level="10.7" data-path="ch10/ch10-07.html">
<a href="../ch10/ch10-07.html">
<i class="fa fa-check"></i>
<b>10.7.</b>
工具
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="11" data-path="ch11/ch11.html">
<a href="../ch11/ch11.html">
<i class="fa fa-check"></i>
<b>11.</b>
測試
</a>
<ul class="articles">
<li class="chapter " data-level="11.1" data-path="ch11/ch11-01.html">
<a href="../ch11/ch11-01.html">
<i class="fa fa-check"></i>
<b>11.1.</b>
go test
</a>
</li>
<li class="chapter " data-level="11.2" data-path="ch11/ch11-02.html">
<a href="../ch11/ch11-02.html">
<i class="fa fa-check"></i>
<b>11.2.</b>
測試函數
</a>
</li>
<li class="chapter " data-level="11.3" data-path="ch11/ch11-03.html">
<a href="../ch11/ch11-03.html">
<i class="fa fa-check"></i>
<b>11.3.</b>
測試覆蓋率
</a>
</li>
<li class="chapter " data-level="11.4" data-path="ch11/ch11-04.html">
<a href="../ch11/ch11-04.html">
<i class="fa fa-check"></i>
<b>11.4.</b>
基準測試
</a>
</li>
<li class="chapter " data-level="11.5" data-path="ch11/ch11-05.html">
<a href="../ch11/ch11-05.html">
<i class="fa fa-check"></i>
<b>11.5.</b>
剖析
</a>
</li>
<li class="chapter " data-level="11.6" data-path="ch11/ch11-06.html">
<a href="../ch11/ch11-06.html">
<i class="fa fa-check"></i>
<b>11.6.</b>
示例函數
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="12" data-path="ch12/ch12.html">
<a href="../ch12/ch12.html">
<i class="fa fa-check"></i>
<b>12.</b>
反射
</a>
<ul class="articles">
<li class="chapter " data-level="12.1" data-path="ch12/ch12-01.html">
<a href="../ch12/ch12-01.html">
<i class="fa fa-check"></i>
<b>12.1.</b>
2015-12-21 04:55:18 +00:00
爲何需要反射?
2015-12-09 07:57:17 +00:00
</a>
</li>
<li class="chapter " data-level="12.2" data-path="ch12/ch12-02.html">
<a href="../ch12/ch12-02.html">
<i class="fa fa-check"></i>
<b>12.2.</b>
reflect.Type和reflect.Value
</a>
</li>
<li class="chapter " data-level="12.3" data-path="ch12/ch12-03.html">
<a href="../ch12/ch12-03.html">
<i class="fa fa-check"></i>
<b>12.3.</b>
Display遞歸打印
</a>
</li>
<li class="chapter " data-level="12.4" data-path="ch12/ch12-04.html">
<a href="../ch12/ch12-04.html">
<i class="fa fa-check"></i>
<b>12.4.</b>
2015-12-21 04:55:18 +00:00
示例: 編碼S表達式
2015-12-09 07:57:17 +00:00
</a>
</li>
<li class="chapter " data-level="12.5" data-path="ch12/ch12-05.html">
<a href="../ch12/ch12-05.html">
<i class="fa fa-check"></i>
<b>12.5.</b>
通過reflect.Value脩改值
</a>
</li>
<li class="chapter " data-level="12.6" data-path="ch12/ch12-06.html">
<a href="../ch12/ch12-06.html">
<i class="fa fa-check"></i>
<b>12.6.</b>
2015-12-21 04:55:18 +00:00
示例: 解碼S表達式
2015-12-09 07:57:17 +00:00
</a>
</li>
<li class="chapter " data-level="12.7" data-path="ch12/ch12-07.html">
<a href="../ch12/ch12-07.html">
<i class="fa fa-check"></i>
<b>12.7.</b>
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獲取結構體字段標識
2015-12-09 07:57:17 +00:00
</a>
</li>
<li class="chapter " data-level="12.8" data-path="ch12/ch12-08.html">
<a href="../ch12/ch12-08.html">
<i class="fa fa-check"></i>
<b>12.8.</b>
顯示一個類型的方法集
</a>
</li>
<li class="chapter " data-level="12.9" data-path="ch12/ch12-09.html">
<a href="../ch12/ch12-09.html">
<i class="fa fa-check"></i>
<b>12.9.</b>
幾點忠告
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="13" data-path="ch13/ch13.html">
<a href="../ch13/ch13.html">
<i class="fa fa-check"></i>
<b>13.</b>
底層編程
</a>
<ul class="articles">
<li class="chapter " data-level="13.1" data-path="ch13/ch13-01.html">
<a href="../ch13/ch13-01.html">
<i class="fa fa-check"></i>
<b>13.1.</b>
unsafe.Sizeof, Alignof 和 Offsetof
</a>
</li>
<li class="chapter " data-level="13.2" data-path="ch13/ch13-02.html">
<a href="../ch13/ch13-02.html">
<i class="fa fa-check"></i>
<b>13.2.</b>
unsafe.Pointer
</a>
</li>
<li class="chapter " data-level="13.3" data-path="ch13/ch13-03.html">
<a href="../ch13/ch13-03.html">
<i class="fa fa-check"></i>
<b>13.3.</b>
示例: 深度相等判斷
</a>
</li>
<li class="chapter " data-level="13.4" data-path="ch13/ch13-04.html">
<a href="../ch13/ch13-04.html">
<i class="fa fa-check"></i>
<b>13.4.</b>
通過cgo調用C代碼
</a>
</li>
<li class="chapter " data-level="13.5" data-path="ch13/ch13-05.html">
<a href="../ch13/ch13-05.html">
<i class="fa fa-check"></i>
<b>13.5.</b>
幾點忠告
</a>
</li>
</ul>
</li>
2015-12-24 06:47:06 +00:00
<li class="chapter " data-level="14" data-path="CONTRIBUTORS.html">
2015-12-09 07:57:17 +00:00
2015-12-24 06:47:06 +00:00
<a href="../CONTRIBUTORS.html">
2015-12-09 07:57:17 +00:00
<i class="fa fa-check"></i>
2015-12-21 04:55:18 +00:00
<b>14.</b>
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2015-12-24 06:47:06 +00:00
附録
2015-12-09 07:57:17 +00:00
</a>
</li>
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<a href="https://www.gitbook.com" target="blank" class="gitbook-link">
本書使用 GitBook 釋出
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<a href="../" >Go语言圣经</a>
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<h2 id="32-&#x6D6E;&#x9EDE;&#x6578;">3.2. &#x6D6E;&#x9EDE;&#x6578;</h2>
2015-12-28 08:08:26 +00:00
<p>Go&#x8A9E;&#x8A00;&#x63D0;&#x4F9B;&#x4E86;&#x5169;&#x7A2E;&#x7CBE;&#x5EA6;&#x7684;&#x6D6E;&#x9EDE;&#x6578;&#xFF0C;float32&#x548C;float64&#x3002;&#x5B83;&#x5011;&#x7684;&#x7B97;&#x8853;&#x898F;&#x8303;&#x7531;IEEE754&#x6D6E;&#x9EDE;&#x6578;&#x56FD;&#x969B;&#x6A19;&#x6E96;&#x5B9A;&#x7FA9;&#xFF0C;&#x8A72;&#x6D6E;&#x9EDE;&#x6578;&#x898F;&#x8303;&#x88AB;&#x6240;&#x6709;&#x73FE;&#x4EE3;&#x7684;CPU&#x652F;&#x6301;&#x3002;</p>
<p>&#x9019;&#x4E9B;&#x6D6E;&#x9EDE;&#x6578;&#x985E;&#x578B;&#x7684;&#x53D6;&#x503C;&#x8303;&#x570D;&#x53EF;&#x4EE5;&#x5F9E;&#x5F88;&#x5FAE;&#x5C0F;&#x5230;&#x5F88;&#x9245;&#x5927;&#x3002;&#x6D6E;&#x9EDE;&#x6578;&#x7684;&#x8303;&#x570D;&#x6975;&#x9650;&#x503C;&#x53EF;&#x4EE5;&#x5728;math&#x5305;&#x627E;&#x5230;&#x3002;&#x5E38;&#x91CF;math.MaxFloat32&#x8868;&#x793A;float32&#x80FD;&#x8868;&#x793A;&#x7684;&#x6700;&#x5927;&#x6578;&#x503C;&#xFF0C;&#x5927;&#x7D04;&#x662F; 3.4e38&#xFF1B;&#x5C0D;&#x61C9;&#x7684;math.MaxFloat64&#x5E38;&#x91CF;&#x5927;&#x7D04;&#x662F;1.8e308&#x3002;&#x5B83;&#x5011;&#x5206;&#x522B;&#x80FD;&#x8868;&#x793A;&#x7684;&#x6700;&#x5C0F;&#x503C;&#x8FD1;&#x4F3C;&#x7232;1.4e-45&#x548C;4.9e-324&#x3002;</p>
<p>&#x4E00;&#x500B;float32&#x985E;&#x578B;&#x7684;&#x6D6E;&#x9EDE;&#x6578;&#x53EF;&#x4EE5;&#x63D0;&#x4F9B;&#x5927;&#x7D04;6&#x500B;&#x5341;&#x9032;&#x88FD;&#x6578;&#x7684;&#x7CBE;&#x5EA6;&#xFF0C;&#x800C;float64&#x5247;&#x53EF;&#x4EE5;&#x63D0;&#x4F9B;&#x7D04;15&#x500B;&#x5341;&#x9032;&#x88FD;&#x6578;&#x7684;&#x7CBE;&#x5EA6;&#xFF1B;&#x901A;&#x5E38;&#x61C9;&#x8A72;&#x512A;&#x5148;&#x4F7F;&#x7528;float64&#x985E;&#x578B;&#xFF0C;&#x56E0;&#x7232;float32&#x985E;&#x578B;&#x7684;&#x7E8D;&#x8A08;&#x8A08;&#x7B97;&#x8AA4;&#x5DEE;&#x5F88;&#x5BB9;&#x6613;&#x64F4;&#x6563;&#xFF0C;&#x4F75;&#x4E14;float32&#x80FD;&#x7CBE;&#x78BA;&#x8868;&#x793A;&#x7684;&#x6B63;&#x6574;&#x6578;&#x4F75;&#x4E0D;&#x662F;&#x5F88;&#x5927;&#xFF08;&#x8B6F;&#x8A3B;&#xFF1A;&#x56E0;&#x7232;float32&#x7684;&#x6709;&#x6548;bit&#x4F4D;&#x96BB;&#x6709;23&#x500B;&#xFF0C;&#x5176;&#x5B83;&#x7684;bit&#x4F4D;&#x7528;&#x65BC;&#x6307;&#x6578;&#x548C;&#x7B26;&#x865F;&#xFF1B;&#x7576;&#x6574;&#x6578;&#x5927;&#x65BC;23bit&#x80FD;&#x8868;&#x9054;&#x7684;&#x8303;&#x570D;&#x6642;&#xFF0C;float32&#x7684;&#x8868;&#x793A;&#x5C07;&#x51FA;&#x73FE;&#x8AA4;&#x5DEE;&#xFF09;&#xFF1A;</p>
2015-12-21 04:55:18 +00:00
<pre><code class="lang-Go"><span class="hljs-keyword">var</span> f <span class="hljs-typename">float32</span> = <span class="hljs-number">16777216</span> <span class="hljs-comment">// 1 &lt;&lt; 24</span>
fmt.Println(f == f+<span class="hljs-number">1</span>) <span class="hljs-comment">// &quot;true&quot;!</span>
</code></pre>
2015-12-28 08:08:26 +00:00
<p>&#x6D6E;&#x9EDE;&#x6578;&#x7684;&#x5B57;&#x9762;&#x503C;&#x53EF;&#x4EE5;&#x76F4;&#x63A5;&#x5BEB;&#x5C0F;&#x6578;&#x90E8;&#x5206;&#xFF0C;&#x50CF;&#x9019;&#x6A23;&#xFF1A;</p>
2015-12-21 04:55:18 +00:00
<pre><code class="lang-Go"><span class="hljs-keyword">const</span> e = <span class="hljs-number">2.71828</span> <span class="hljs-comment">// (approximately)</span>
</code></pre>
2015-12-28 08:08:26 +00:00
<p>&#x5C0F;&#x6578;&#x9EDE;&#x524D;&#x9762;&#x6216;&#x5F8C;&#x9762;&#x7684;&#x6578;&#x5B57;&#x90FD;&#x53EF;&#x80FD;&#x88AB;&#x7701;&#x7565;&#xFF08;&#x4F8B;&#x5982;.707&#x6216;1.&#xFF09;&#x3002;&#x5F88;&#x5C0F;&#x6216;&#x5F88;&#x5927;&#x7684;&#x6578;&#x6700;&#x597D;&#x7528;&#x79D1;&#x5B78;&#x8A08;&#x6578;&#x6CD5;&#x66F8;&#x5BEB;&#xFF0C;&#x901A;&#x904E;e&#x6216;E&#x4F86;&#x6307;&#x5B9A;&#x6307;&#x6578;&#x90E8;&#x5206;&#xFF1A;</p>
<pre><code class="lang-Go"><span class="hljs-keyword">const</span> Avogadro = <span class="hljs-number">6.02214129e23</span> <span class="hljs-comment">// &#x963F;&#x4F0F;&#x4F3D;&#x5FB7;&#x7F85;&#x5E38;&#x6578;</span>
<span class="hljs-keyword">const</span> Planck = <span class="hljs-number">6.62606957e-34</span> <span class="hljs-comment">// &#x666E;&#x6717;&#x524B;&#x5E38;&#x6578;</span>
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</code></pre>
2015-12-28 08:08:26 +00:00
<p>&#x7528;Printf&#x51FD;&#x6578;&#x7684;%g&#x53C3;&#x6578;&#x6253;&#x5370;&#x6D6E;&#x9EDE;&#x6578;&#xFF0C;&#x5C07;&#x91C7;&#x7528;&#x66F4;&#x7DCA;&#x6E4A;&#x7684;&#x8868;&#x793A;&#x5F62;&#x5F0F;&#x6253;&#x5370;&#xFF0C;&#x4F75;&#x63D0;&#x4F9B;&#x8DB3;&#x5920;&#x7684;&#x7CBE;&#x5EA6;&#xFF0C;&#x4F46;&#x662F;&#x5C0D;&#x61C9;&#x8868;&#x683C;&#x7684;&#x6578;&#x64DA;&#xFF0C;&#x4F7F;&#x7528;%e&#xFF08;&#x5E36;&#x6307;&#x6578;&#xFF09;&#x6216;%f&#x7684;&#x5F62;&#x5F0F;&#x6253;&#x5370;&#x53EF;&#x80FD;&#x66F4;&#x5408;&#x9069;&#x3002;&#x6240;&#x6709;&#x7684;&#x9019;&#x4E09;&#x500B;&#x6253;&#x5370;&#x5F62;&#x5F0F;&#x90FD;&#x53EF;&#x4EE5;&#x6307;&#x5B9A;&#x6253;&#x5370;&#x7684;&#x5BEC;&#x5EA6;&#x548C;&#x63A7;&#x88FD;&#x6253;&#x5370;&#x7CBE;&#x5EA6;&#x3002;</p>
2015-12-21 04:55:18 +00:00
<pre><code class="lang-Go"><span class="hljs-keyword">for</span> x := <span class="hljs-number">0</span>; x &lt; <span class="hljs-number">8</span>; x++ {
fmt.Printf(<span class="hljs-string">&quot;x = %d e^x = %8.3f\n&quot;</span>, x, math.Exp(<span class="hljs-typename">float64</span>(x)))
}
</code></pre>
2015-12-28 08:08:26 +00:00
<p>&#x4E0A;&#x9762;&#x4EE3;&#x78BC;&#x6253;&#x5370;e&#x7684;&#x51AA;&#xFF0C;&#x6253;&#x5370;&#x7CBE;&#x5EA6;&#x662F;&#x5C0F;&#x6578;&#x9EDE;&#x5F8C;&#x4E09;&#x500B;&#x5C0F;&#x6578;&#x7CBE;&#x5EA6;&#x548C;8&#x500B;&#x5B57;&#x7B26;&#x5BEC;&#x5EA6;&#xFF1A;</p>
2015-12-21 04:55:18 +00:00
<pre><code>x = 0 e^x = 1.000
x = 1 e^x = 2.718
x = 2 e^x = 7.389
x = 3 e^x = 20.086
x = 4 e^x = 54.598
x = 5 e^x = 148.413
x = 6 e^x = 403.429
x = 7 e^x = 1096.633
2015-12-28 08:08:26 +00:00
</code></pre><p>math&#x5305;&#x4E2D;&#x9664;&#x4E86;&#x63D0;&#x4F9B;&#x5927;&#x91CF;&#x5E38;&#x7528;&#x7684;&#x6578;&#x5B78;&#x51FD;&#x6578;&#x5916;&#xFF0C;&#x9084;&#x63D0;&#x4F9B;&#x4E86;IEEE754&#x6D6E;&#x9EDE;&#x6578;&#x6A19;&#x6E96;&#x4E2D;&#x5B9A;&#x7FA9;&#x7684;&#x7279;&#x6B8A;&#x503C;&#x7684;&#x5275;&#x5EFA;&#x548C;&#x6E2C;&#x8A66;&#xFF1A;&#x6B63;&#x7121;&#x7AAE;&#x5927;&#x548C;&#x8CA0;&#x7121;&#x7AAE;&#x5927;&#xFF0C;&#x5206;&#x522B;&#x7528;&#x65BC;&#x8868;&#x793A;&#x592A;&#x5927;&#x6EA2;&#x51FA;&#x7684;&#x6578;&#x5B57;&#x548C;&#x9664;&#x96F6;&#x7684;&#x7D50;&#x679C;&#xFF1B;&#x9084;&#x6709;NaN&#x975E;&#x6578;&#xFF0C;&#x4E00;&#x822C;&#x7528;&#x65BC;&#x8868;&#x793A;&#x7121;&#x6548;&#x7684;&#x9664;&#x6CD5;&#x64CD;&#x4F5C;&#x7D50;&#x679C;0/0&#x6216;Sqrt(-1).</p>
2015-12-21 04:55:18 +00:00
<pre><code class="lang-Go"><span class="hljs-keyword">var</span> z <span class="hljs-typename">float64</span>
fmt.Println(z, -z, <span class="hljs-number">1</span>/z, -<span class="hljs-number">1</span>/z, z/z) <span class="hljs-comment">// &quot;0 -0 +Inf -Inf NaN&quot;</span>
</code></pre>
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<p>&#x51FD;&#x6578;math.IsNaN&#x7528;&#x65BC;&#x6E2C;&#x8A66;&#x4E00;&#x500B;&#x6578;&#x662F;&#x5426;&#x662F;&#x975E;&#x6578;NaN&#xFF0C;math.NaN&#x5247;&#x8FD4;&#x8FF4;&#x975E;&#x6578;&#x5C0D;&#x61C9;&#x7684;&#x503C;&#x3002;&#x96D6;&#x7136;&#x53EF;&#x4EE5;&#x7528;math.NaN&#x4F86;&#x8868;&#x793A;&#x4E00;&#x500B;&#x975E;&#x6CD5;&#x7684;&#x7D50;&#x679C;&#xFF0C;&#x4F46;&#x662F;&#x6E2C;&#x8A66;&#x4E00;&#x500B;&#x7D50;&#x679C;&#x662F;&#x5426;&#x662F;&#x975E;&#x6578;NaN&#x5247;&#x662F;&#x5145;&#x6EFF;&#x98A8;&#x96AA;&#x7684;&#xFF0C;&#x56E0;&#x7232;NaN&#x548C;&#x4EFB;&#x4F55;&#x6578;&#x90FD;&#x662F;&#x4E0D;&#x76F8;&#x7B49;&#x7684;&#xFF08;&#x8B6F;&#x8A3B;&#xFF1A;&#x5728;&#x6D6E;&#x9EDE;&#x6578;&#x4E2D;&#xFF0C;NaN&#x3001;&#x6B63;&#x7121;&#x7AAE;&#x5927;&#x548C;&#x8CA0;&#x7121;&#x7AAE;&#x5927;&#x90FD;&#x4E0D;&#x662F;&#x552F;&#x4E00;&#x7684;&#xFF0C;&#x6BCF;&#x500B;&#x90FD;&#x6709;&#x975E;&#x5E38;&#x591A;&#x7A2E;&#x7684;bit&#x6A21;&#x5F0F;&#x8868;&#x793A;&#xFF09;&#xFF1A;</p>
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<pre><code class="lang-Go">nan := math.NaN()
fmt.Println(nan == nan, nan &lt; nan, nan &gt; nan) <span class="hljs-comment">// &quot;false false false&quot;</span>
</code></pre>
2015-12-28 08:08:26 +00:00
<p>&#x5982;&#x679C;&#x4E00;&#x500B;&#x51FD;&#x6578;&#x8FD4;&#x8FF4;&#x7684;&#x6D6E;&#x9EDE;&#x6578;&#x7D50;&#x679C;&#x53EF;&#x80FD;&#x5931;&#x6557;&#xFF0C;&#x6700;&#x597D;&#x7684;&#x505A;&#x6CD5;&#x662F;&#x7528;&#x55AE;&#x7368;&#x7684;&#x6A19;&#x8A8C;&#x5831;&#x544A;&#x5931;&#x6557;&#xFF0C;&#x50CF;&#x9019;&#x6A23;&#xFF1A;</p>
2015-12-21 04:55:18 +00:00
<pre><code class="lang-Go"><span class="hljs-keyword">func</span> compute() (value <span class="hljs-typename">float64</span>, ok <span class="hljs-typename">bool</span>) {
<span class="hljs-comment">// ...</span>
<span class="hljs-keyword">if</span> failed {
<span class="hljs-keyword">return</span> <span class="hljs-number">0</span>, <span class="hljs-constant">false</span>
}
<span class="hljs-keyword">return</span> result, <span class="hljs-constant">true</span>
}
</code></pre>
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<p>&#x63A5;&#x4E0B;&#x4F86;&#x7684;&#x7A0B;&#x5E8F;&#x6F14;&#x793A;&#x4E86;&#x901A;&#x904E;&#x6D6E;&#x9EDE;&#x8A08;&#x7B97;&#x751F;&#x6210;&#x7684;&#x5716;&#x5F62;&#x3002;&#x5B83;&#x662F;&#x5E36;&#x6709;&#x5169;&#x500B;&#x53C3;&#x6578;&#x7684;z = f(x, y)&#x51FD;&#x6578;&#x7684;&#x4E09;&#x7DAD;&#x5F62;&#x5F0F;&#xFF0C;&#x4F7F;&#x7528;&#x4E86;&#x53EF;&#x7E2E;&#x653E;&#x77E2;&#x91CF;&#x5716;&#x5F62;&#xFF08;SVG&#xFF09;&#x683C;&#x5F0F;&#x8F38;&#x51FA;&#xFF0C;SVG&#x662F;&#x4E00;&#x500B;&#x7528;&#x65BC;&#x77E2;&#x91CF;&#x7DDA;&#x7E6A;&#x88FD;&#x7684;XML&#x6A19;&#x6E96;&#x3002;&#x5716;3.1&#x986F;&#x793A;&#x4E86;sin(r)/r&#x51FD;&#x6578;&#x7684;&#x8F38;&#x51FA;&#x5716;&#x5F62;&#xFF0C;&#x5176;&#x4E2D;r&#x662F;sqrt(x<em>x+y</em>y)&#x3002;</p>
2015-12-21 04:55:18 +00:00
<p><img src="../images/ch3-01.png" alt=""></p>
<pre><code class="lang-Go">gopl.io/ch3/surface
<span class="hljs-comment">// Surface computes an SVG rendering of a 3-D surface function.</span>
<span class="hljs-keyword">package</span> main
<span class="hljs-keyword">import</span> (
<span class="hljs-string">&quot;fmt&quot;</span>
<span class="hljs-string">&quot;math&quot;</span>
)
<span class="hljs-keyword">const</span> (
width, height = <span class="hljs-number">600</span>, <span class="hljs-number">320</span> <span class="hljs-comment">// canvas size in pixels</span>
cells = <span class="hljs-number">100</span> <span class="hljs-comment">// number of grid cells</span>
xyrange = <span class="hljs-number">30.0</span> <span class="hljs-comment">// axis ranges (-xyrange..+xyrange)</span>
xyscale = width / <span class="hljs-number">2</span> / xyrange <span class="hljs-comment">// pixels per x or y unit</span>
zscale = height * <span class="hljs-number">0.4</span> <span class="hljs-comment">// pixels per z unit</span>
angle = math.Pi / <span class="hljs-number">6</span> <span class="hljs-comment">// angle of x, y axes (=30&#xB0;)</span>
)
<span class="hljs-keyword">var</span> sin30, cos30 = math.Sin(angle), math.Cos(angle) <span class="hljs-comment">// sin(30&#xB0;), cos(30&#xB0;)</span>
<span class="hljs-keyword">func</span> main() {
fmt.Printf(<span class="hljs-string">&quot;&lt;svg xmlns=&apos;http://www.w3.org/2000/svg&apos; &quot;</span>+
<span class="hljs-string">&quot;style=&apos;stroke: grey; fill: white; stroke-width: 0.7&apos; &quot;</span>+
<span class="hljs-string">&quot;width=&apos;%d&apos; height=&apos;%d&apos;&gt;&quot;</span>, width, height)
<span class="hljs-keyword">for</span> i := <span class="hljs-number">0</span>; i &lt; cells; i++ {
<span class="hljs-keyword">for</span> j := <span class="hljs-number">0</span>; j &lt; cells; j++ {
ax, ay := corner(i+<span class="hljs-number">1</span>, j)
bx, by := corner(i, j)
cx, cy := corner(i, j+<span class="hljs-number">1</span>)
dx, dy := corner(i+<span class="hljs-number">1</span>, j+<span class="hljs-number">1</span>)
fmt.Printf(<span class="hljs-string">&quot;&lt;polygon points=&apos;%g,%g %g,%g %g,%g %g,%g&apos;/&gt;\n&quot;</span>,
ax, ay, bx, by, cx, cy, dx, dy)
}
}
fmt.Println(<span class="hljs-string">&quot;&lt;/svg&gt;&quot;</span>)
}
<span class="hljs-keyword">func</span> corner(i, j <span class="hljs-typename">int</span>) (<span class="hljs-typename">float64</span>, <span class="hljs-typename">float64</span>) {
<span class="hljs-comment">// Find point (x,y) at corner of cell (i,j).</span>
x := xyrange * (<span class="hljs-typename">float64</span>(i)/cells - <span class="hljs-number">0.5</span>)
y := xyrange * (<span class="hljs-typename">float64</span>(j)/cells - <span class="hljs-number">0.5</span>)
<span class="hljs-comment">// Compute surface height z.</span>
z := f(x, y)
<span class="hljs-comment">// Project (x,y,z) isometrically onto 2-D SVG canvas (sx,sy).</span>
sx := width/<span class="hljs-number">2</span> + (x-y)*cos30*xyscale
sy := height/<span class="hljs-number">2</span> + (x+y)*sin30*xyscale - z*zscale
<span class="hljs-keyword">return</span> sx, sy
}
<span class="hljs-keyword">func</span> f(x, y <span class="hljs-typename">float64</span>) <span class="hljs-typename">float64</span> {
r := math.Hypot(x, y) <span class="hljs-comment">// distance from (0,0)</span>
<span class="hljs-keyword">return</span> math.Sin(r) / r
}
</code></pre>
2015-12-28 08:08:26 +00:00
<p>&#x8981;&#x8A3B;&#x610F;&#x7684;&#x662F;corner&#x51FD;&#x6578;&#x8FD4;&#x8FF4;&#x4E86;&#x5169;&#x500B;&#x7D50;&#x679C;&#xFF0C;&#x5206;&#x522B;&#x5C0D;&#x61C9;&#x6BCF;&#x500B;&#x7DB2;&#x683C;&#x9802;&#x9EDE;&#x7684;&#x5750;&#x6A19;&#x53C3;&#x6578;&#x3002;</p>
<p>&#x8981;&#x89E3;&#x91CB;&#x9019;&#x500B;&#x7A0B;&#x5E8F;&#x662F;&#x5982;&#x4F55;&#x5DE5;&#x4F5C;&#x7684;&#x9700;&#x8981;&#x4E00;&#x4E9B;&#x57FA;&#x672C;&#x7684;&#x5E7E;&#x4F55;&#x5B78;&#x77E5;&#x8B58;&#xFF0C;&#x4F46;&#x662F;&#x6211;&#x5011;&#x53EF;&#x4EE5;&#x8DF3;&#x904E;&#x5E7E;&#x4F55;&#x5B78;&#x539F;&#x7406;&#xFF0C;&#x56E0;&#x7232;&#x7A0B;&#x5E8F;&#x7684;&#x91CD;&#x9EDE;&#x662F;&#x6F14;&#x793A;&#x6D6E;&#x9EDE;&#x6578;&#x904B;&#x7B97;&#x3002;&#x7A0B;&#x5E8F;&#x7684;&#x672C;&#x8CEA;&#x662F;&#x4E09;&#x500B;&#x4E0D;&#x540C;&#x7684;&#x5750;&#x6A19;&#x7E6B;&#x4E2D;&#x6620;&#x5C04;&#x95DC;&#x7E6B;&#xFF0C;&#x5982;&#x5716;3.2&#x6240;&#x793A;&#x3002;&#x7B2C;&#x4E00;&#x500B;&#x662F;100x100&#x7684;&#x4E8C;&#x7DAD;&#x7DB2;&#x683C;&#xFF0C;&#x5C0D;&#x61C9;&#x6574;&#x6578;&#x6574;&#x6578;&#x5750;&#x6A19;(i,j)&#xFF0C;&#x5F9E;&#x9060;&#x8655;&#x7684;(0, 0)&#x4F4D;&#x7F6E;&#x958B;&#x59CB;&#x3002;&#x6211;&#x5011;&#x5F9E;&#x9060;&#x8655;&#x5411;&#x524D;&#x9762;&#x7E6A;&#x88FD;&#xFF0C;&#x56E0;&#x6B64;&#x9060;&#x8655;&#x5148;&#x7E6A;&#x88FD;&#x7684;&#x591A;&#x908A;&#x5F62;&#x6709;&#x53EF;&#x80FD;&#x88AB;&#x524D;&#x9762;&#x5F8C;&#x7E6A;&#x88FD;&#x7684;&#x591A;&#x908A;&#x5F62;&#x8986;&#x84CB;&#x3002;</p>
<p>&#x7B2C;&#x4E8C;&#x500B;&#x5750;&#x6A19;&#x7E6B;&#x662F;&#x4E00;&#x500B;&#x4E09;&#x7DAD;&#x7684;&#x7DB2;&#x683C;&#x6D6E;&#x9EDE;&#x5750;&#x6A19;(x,y,z)&#xFF0C;&#x5176;&#x4E2D;x&#x548C;y&#x662F;i&#x548C;j&#x7684;&#x7DDA;&#x6027;&#x51FD;&#x6578;&#xFF0C;&#x901A;&#x904E;&#x5E73;&#x79FB;&#x8F49;&#x63DB;&#x4F4D;&#x7DB2;&#x683C;&#x55AE;&#x5143;&#x7684;&#x4E2D;&#x5FC3;&#xFF0C;&#x7136;&#x5F8C;&#x7528;xyrange&#x7E6B;&#x6578;&#x7E2E;&#x653E;&#x3002;&#x9AD8;&#x5EA6;z&#x662F;&#x51FD;&#x6578;f(x,y)&#x7684;&#x503C;&#x3002;</p>
<p>&#x7B2C;&#x4E09;&#x500B;&#x5750;&#x6A19;&#x7E6B;&#x662F;&#x4E00;&#x500B;&#x4E8C;&#x7DAD;&#x7684;&#x7575;&#x5E03;&#xFF0C;&#x8D77;&#x9EDE;(0,0)&#x5728;&#x5DE6;&#x4E0A;&#x89D2;&#x3002;&#x7575;&#x5E03;&#x4E2D;&#x9EDE;&#x7684;&#x5750;&#x6A19;&#x7528;(sx, sy)&#x8868;&#x793A;&#x3002;&#x6211;&#x5011;&#x4F7F;&#x7528;&#x7B49;&#x89D2;&#x6295;&#x5F71;&#x5C07;&#x4E09;&#x7DAD;&#x9EDE;</p>
2015-12-21 04:55:18 +00:00
<p><img src="../images/ch3-02.png" alt=""></p>
2015-12-28 08:08:26 +00:00
<p>(x,y,z)&#x6295;&#x5F71;&#x5230;&#x4E8C;&#x7DAD;&#x7684;&#x7575;&#x5E03;&#x4E2D;&#x3002;&#x7575;&#x5E03;&#x4E2D;&#x5F9E;&#x9060;&#x8655;&#x5230;&#x53F3;&#x908A;&#x7684;&#x9EDE;&#x5C0D;&#x61C9;&#x8F03;&#x5927;&#x7684;x&#x503C;&#x548C;&#x8F03;&#x5927;&#x7684;y&#x503C;&#x3002;&#x4F75;&#x4E14;&#x7575;&#x5E03;&#x4E2D;x&#x548C;y&#x503C;&#x8D8A;&#x5927;&#xFF0C;&#x5247;&#x5C0D;&#x61C9;&#x7684;z&#x503C;&#x8D8A;&#x5C0F;&#x3002;x&#x548C;y&#x7684;&#x5782;&#x76F4;&#x548C;&#x6C34;&#x5E73;&#x7E2E;&#x653E;&#x7E6B;&#x6578;&#x4F86;&#x81EA;30&#x5EA6;&#x89D2;&#x7684;&#x6B63;&#x7D43;&#x548C;&#x9918;&#x7D43;&#x503C;&#x3002;z&#x7684;&#x7E2E;&#x653E;&#x7E6B;&#x6578;0.4&#xFF0C;&#x662F;&#x4E00;&#x500B;&#x4EFB;&#x610F;&#x9078;&#x64C7;&#x7684;&#x53C3;&#x6578;&#x3002;</p>
<p>&#x5C0D;&#x65BC;&#x4E8C;&#x7DAD;&#x7DB2;&#x683C;&#x4E2D;&#x7684;&#x6BCF;&#x4E00;&#x500B;&#x7DB2;&#x683C;&#x55AE;&#x5143;&#xFF0C;main&#x51FD;&#x6578;&#x8A08;&#x7B97;&#x55AE;&#x5143;&#x7684;&#x56DB;&#x500B;&#x9802;&#x9EDE;&#x5728;&#x7575;&#x5E03;&#x4E2D;&#x5C0D;&#x61C9;&#x591A;&#x908A;&#x5F62;ABCD&#x7684;&#x9802;&#x9EDE;&#xFF0C;&#x5176;&#x4E2D;B&#x5C0D;&#x61C9;(i,j)&#x9802;&#x9EDE;&#x4F4D;&#x7F6E;&#xFF0C;A&#x3001;C&#x548C;D&#x662F;&#x5176;&#x5B83;&#x76F8;&#x9130;&#x7684;&#x9802;&#x9EDE;&#xFF0C;&#x7136;&#x5F8C;&#x8F38;&#x51FA;SVG&#x7684;&#x7E6A;&#x88FD;&#x6307;&#x4EE4;&#x3002;</p>
<p><strong>&#x7DF4;&#x7FD2; 3.1&#xFF1A;</strong> &#x5982;&#x679C;f&#x51FD;&#x6578;&#x8FD4;&#x8FF4;&#x7684;&#x662F;&#x7121;&#x9650;&#x88FD;&#x7684;float64&#x503C;&#xFF0C;&#x90A3;&#x9EBD;SVG&#x6587;&#x4EF6;&#x53EF;&#x80FD;&#x8F38;&#x51FA;&#x7121;&#x6548;&#x7684;<polygon></polygon>&#x591A;&#x908A;&#x5F62;&#x5143;&#x7D20;&#xFF08;&#x96D6;&#x7136;&#x8A31;&#x591A;SVG&#x6E32;&#x67D3;&#x5668;&#x6703;&#x59A5;&#x5584;&#x8655;&#x7406;&#x9019;&#x985E;&#x554F;&#x984C;&#xFF09;&#x3002;&#x8129;&#x6539;&#x7A0B;&#x5E8F;&#x8DF3;&#x904E;&#x7121;&#x6548;&#x7684;&#x591A;&#x908A;&#x5F62;&#x3002;</p>
<p><strong>&#x7DF4;&#x7FD2; 3.2&#xFF1A;</strong> &#x8A66;&#x9A57;math&#x5305;&#x4E2D;&#x5176;&#x4ED6;&#x51FD;&#x6578;&#x7684;&#x6E32;&#x67D3;&#x5716;&#x5F62;&#x3002;&#x4F60;&#x662F;&#x5426;&#x80FD;&#x8F38;&#x51FA;&#x4E00;&#x500B;egg box&#x3001;moguls&#x6216;a saddle&#x5716;&#x6848;?</p>
<p><strong>&#x7DF4;&#x7FD2; 3.3&#xFF1A;</strong> &#x6839;&#x64DA;&#x9AD8;&#x5EA6;&#x7D66;&#x6BCF;&#x500B;&#x591A;&#x908A;&#x5F62;&#x4E0A;&#x8272;&#xFF0C;&#x90A3;&#x6A23;&#x5CEF;&#x503C;&#x90E8;&#x5C07;&#x662F;&#x7D05;&#x8272;(#ff0000)&#xFF0C;&#x8C37;&#x90E8;&#x5C07;&#x662F;&#x85CD;&#x8272;(#0000ff)&#x3002;</p>
<p><strong>&#x7DF4;&#x7FD2; 3.4&#xFF1A;</strong> &#x53C3;&#x8003;1.7&#x7BC0;Lissajous&#x4F8B;&#x5B50;&#x7684;&#x51FD;&#x6578;&#xFF0C;&#x69CB;&#x9020;&#x4E00;&#x500B;web&#x670D;&#x52D9;&#x5668;&#xFF0C;&#x7528;&#x65BC;&#x8A08;&#x7B97;&#x51FD;&#x6578;&#x9EB4;&#x9762;&#x7136;&#x5F8C;&#x8FD4;&#x8FF4;SVG&#x6578;&#x64DA;&#x7D66;&#x5BA2;&#x6236;&#x7AEF;&#x3002;&#x670D;&#x52D9;&#x5668;&#x5FC5;&#x9B1A;&#x8A2D;&#x7F6E;Content-Type&#x982D;&#x90E8;&#xFF1A;</p>
2015-12-21 04:55:18 +00:00
<pre><code class="lang-Go">w.Header().Set(<span class="hljs-string">&quot;Content-Type&quot;</span>, <span class="hljs-string">&quot;image/svg+xml&quot;</span>)
</code></pre>
2015-12-28 08:08:26 +00:00
<p>&#xFF08;&#x9019;&#x4E00;&#x6B65;&#x5728;Lissajous&#x4F8B;&#x5B50;&#x4E2D;&#x4E0D;&#x662F;&#x5FC5;&#x9B1A;&#x7684;&#xFF0C;&#x56E0;&#x7232;&#x670D;&#x52D9;&#x5668;&#x4F7F;&#x7528;&#x6A19;&#x6E96;&#x7684;PNG&#x5716;&#x50CF;&#x683C;&#x5F0F;&#xFF0C;&#x53EF;&#x4EE5;&#x6839;&#x64DA;&#x524D;&#x9762;&#x7684;512&#x500B;&#x5B57;&#x7BC0;&#x81EA;&#x52D5;&#x8F38;&#x51FA;&#x5C0D;&#x61C9;&#x7684;&#x982D;&#x90E8;&#x3002;&#xFF09;&#x5141;&#x8A31;&#x5BA2;&#x6236;&#x7AEF;&#x901A;&#x904E;HTTP&#x8ACB;&#x6C42;&#x53C3;&#x6578;&#x8A2D;&#x7F6E;&#x9AD8;&#x5EA6;&#x3001;&#x5BEC;&#x5EA6;&#x548C;&#x9854;&#x8272;&#x7B49;&#x53C3;&#x6578;&#x3002;</p>
2015-12-09 07:57:17 +00:00
</section>
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