抛物线法.frm

完整的数值模拟软件

VERSION 5.00
Begin VB.Form Form23 
   BackColor       =   &H00FFFFFF&
   Caption         =   "抛物线法"
   ClientHeight    =   7605
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   7515
   LinkTopic       =   "Form16"
   ScaleHeight     =   7605
   ScaleWidth      =   7515
   StartUpPosition =   3  '窗口缺省
   Begin VB.CommandButton Command1 
      Caption         =   "抛物线法"
      BeginProperty Font 
         Name            =   "宋体"
         Size            =   12
         Charset         =   134
         Weight          =   700
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   615
      Left            =   2760
      TabIndex        =   0
      Top             =   120
      Width           =   1815
   End
End
Attribute VB_Name = "Form23"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Private Sub Command1_Click()
x0 = 1
X1 = 2
X2 = 3

k = 1
Cls
Print: Print: Print: Print: Print: Print: Print: Print: Print
Do While True
   x = x0
   y0 = x ^ 3 + x - 4
   x = X1
   Y1 = x ^ 3 + x - 4
   x = X2
   Y2 = x ^ 3 + x - 4
   i = (X2 - X1) / (X1 - x0)
   j = 1 + i
   a = y0 * i ^ 2 - Y1 * i * j + Y2 * i
   b = y0 * i ^ 2 - Y1 * j ^ 2 + Y2 * (i + j)
   c = Y2 * j
   m = b + (b ^ 2 - 4 * a * c) ^ 0.5
   n = b - (b ^ 2 - 4 * a * c) ^ 0.5
   If b < 0 Then
      l = (-2) * c / n
   Else
      l = (-2) * c / m
   End If
   
   x3 = X2 + l * (X2 - X1)
   x = x3
   y = x ^ 3 + x - 4
   Print Tab(7); "k="; k, "x0="; Int(x0 * 1000000 + 0.5) / 1000000, "y0="; Int(y0 * 1000000 + 0.5) / 1000000, "x1="; Int(X1 * 1000000 + 0.5) / 1000000, "y1="; Int(Y1 * 1000000 + 0.5) / 1000000, "x2="; Int(X2 * 1000000 + 0.5) / 1000000, "y2="; Int(Y2 * 1000000 + 0.5) / 1000000, "x="; Int(x * 1000000 + 0.5) / 1000000, "y="; Int(y * 1000000 + 0.5) / 1000000
 
   e = Abs(y)
   MsgBox "按任意键继续"
   If e < 0.00001 Then
     Exit Do
   Else
      x0 = X1
      y0 = Y1
      X1 = X2
      Y1 = Y2
      X2 = x
      Y2 = y
   End If
   k = k + 1
Loop
Print
Print Tab(7); "经过"; k; "次后得到方程的解为："; "x="; Int(x * 1000000 + 0.5) / 1000000
End Sub