pi.frm

Visual Basic课程举例1 有很好的例题

VERSION 5.00
Begin VB.Form Form1 
   AutoRedraw      =   -1  'True
   Caption         =   "割圆术求圆周率"
   ClientHeight    =   5790
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   4695
   LinkTopic       =   "Form1"
   Picture         =   "Pi.frx":0000
   ScaleHeight     =   5790
   ScaleWidth      =   4695
   StartUpPosition =   3  '窗口缺省
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
'割圆术求圆周率
'制图，编程，曹新国，2004年2月
Private Sub Form_Click()
    Dim R#, G#, S#, P#, C%
    C = 0                   '次数计数
    S = 2                   '初始边数的一半(马上就要倍增)
    R = Sqr(2)
    Do
        S = S * 2           '边数增倍
        R = R / 2           '边长减半
        C = C + 1           '次数加1
        P = S * R           '保留初始近似值，精度控制用
        G = Sqr(1 - R ^ 2)              '求出绿色部分
        R = Sqr(R ^ 2 + (1 - G) ^ 2)    '求出红色部分
        Print "次数：" & C; Tab(12); "边数：" & S; Tab(28); "近似值：" & S * R
    Loop While S * R - P > 0.000000000000001
End Sub