From feb3465accc7cf9a3a2f316d4f0fc64b50847e0f Mon Sep 17 00:00:00 2001
From: gelosie <gelosie.wang@gmail.com>
Date: Thu, 20 Sep 2012 14:59:35 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A01.2=E8=8A=82=E7=9A=84?=
 =?UTF-8?q?=E4=BB=A3=E7=A0=81?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 1.2.md          |  2 ++
 src/1.2/main.go | 13 +++++++++++++
 src/1.2/sqrt.go | 11 +++++++++++
 3 files changed, 26 insertions(+)
 create mode 100644 src/1.2/main.go
 create mode 100644 src/1.2/sqrt.go

diff --git a/1.2.md b/1.2.md
index a9558458..3b16849f 100644
--- a/1.2.md
+++ b/1.2.md
@@ -2,6 +2,8 @@
 
 ## GOPATH设置
   go 命令依赖一个重要的环境变量：$GOPATH<sup>1</sup>
+  
+  *（注：这个不是Go安装目录。下面以笔者的工作目录为说明，请替换自己机器上的工作目录。）*
 
   在类似 Unix 环境大概这样设置：
 
diff --git a/src/1.2/main.go b/src/1.2/main.go
new file mode 100644
index 00000000..328acd54
--- /dev/null
+++ b/src/1.2/main.go
@@ -0,0 +1,13 @@
+// 章节 1.2
+// $GOPATH/src/mathapp/main.go
+
+package main
+
+import (
+	"fmt"
+	"mymath"
+)
+
+func main() {
+	fmt.Printf("Hello, world.  Sqrt(2) = %v\n", mymath.Sqrt(2))
+}
diff --git a/src/1.2/sqrt.go b/src/1.2/sqrt.go
new file mode 100644
index 00000000..2fb5d8fc
--- /dev/null
+++ b/src/1.2/sqrt.go
@@ -0,0 +1,11 @@
+// 章节 1.2
+// $GOPATH/src/mymath/sqrt.go
+package mymath
+
+func Sqrt(x float64) float64 {
+	z := 0.0
+	for i := 0; i < 1000; i++ {
+		z -= (z*z - x) / (2 * x)
+	}
+	return z
+}