改进的欧拉法.frm

完整的数值模拟软件

VERSION 5.00
Begin VB.Form Form16 
   BackColor       =   &H00FFFFFF&
   Caption         =   "改进的欧拉法"
   ClientHeight    =   7260
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   10755
   LinkTopic       =   "Form22"
   ScaleHeight     =   7260
   ScaleWidth      =   10755
   StartUpPosition =   3  '窗口缺省
   Begin VB.CommandButton Command1 
      Caption         =   "改进的欧拉法"
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   10.5
         Charset         =   134
         Weight          =   700
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   615
      Left            =   1200
      TabIndex        =   0
      Top             =   960
      Width           =   2055
   End
End
Attribute VB_Name = "Form16"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Private Sub Command1_Click()
Rem 输出坐标轴

Dim y1(2), y2(2)

y1(1) = 1.2
y2(1) = 0
y3 = 0
y4 = -1.04936
u = 0.012129
v = 1 - u
h = InputBox("请输入h:", "")
h = Val(h)
n = 6.2 / h

Cls
x0 = 7000
y0 = 5000

Line (200, y0)-(15000, y0)
Line (x0, 500)-(x0, 9000)

t0 = 2000


i = 2
Do While i <= n
   r1 = Sqr((y1(1) + u) * (y1(1) + u) + y2(1) * y2(1))
   r1 = r1 ^ 3
   r2 = Sqr((y1(1) - v) * (y1(1) - v) + y2(1) * y2(1))
   r2 = r2 ^ 3
   
   k1 = y3
   l1 = y4
   m1 = y1(1) + 2 * y4 - v * (y1(1) + u) / r1 - u * (y1(1) - v) / r2
   n1 = y2(1) - 2 * y3 - v * y2(1) / r1 - u * y2(1) / r2
   
   r1 = Sqr((y1(1) + h * k1 / 2 + u) * (y1(1) + h * k1 / 2 + u) + (y2(1) + h * l1 / 2) * (y2(1) + h * l1 / 2))
   r1 = r1 ^ 3
   r2 = Sqr((y1(1) + h * k1 / 2 - v) * (y1(1) + h * k1 / 2 - v) + (y2(1) + h * l1 / 2) * (y2(1) + h * l1 / 2))
   r2 = r2 ^ 3
   k2 = y3 + h * m1 / 2
   l2 = y4 + h * n1 / 2
   m2 = y1(1) + h * k1 / 2 + 2 * (y4 + h * n1 / 2) - v * (y1(1) + h * k1 / 2 + u) / r1 - u * (y1(1) + h * k1 / 2 - v) / r2
   n2 = y2(1) + h * l1 / 2 - 2 * (y3 + h * m1 / 2) - v * (y2(1) + h * l1 / 2) / r1 - u * (y2(1) + h * l1 / 2) / r2
      
   
   y1(2) = y1(1) + h * (k1 + k2) / 2
   y2(2) = y2(1) + h * (l1 + l2) / 2
   y3 = y3 + h * (m1 + m2) / 2
   y4 = y4 + h * (n1 + n2) / 2
   
   Line (x0 + y1(1) * t0, y0 - y2(1) * t0)-(x0 + y1(2) * t0, y0 - y2(2) * t0)
   
   y1(1) = y1(2)
   y2(1) = y2(2)

   i = i + 1
Loop


i = 1
Do While i <= n - 1
  i = i + 1
Loop
End Sub