form1.frm

大学数学系必学的数值分析的雅可必逼近的程序

VERSION 5.00
Begin VB.Form Form1 
   ClientHeight    =   6555
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   7965
   LinkTopic       =   "Form1"
   ScaleHeight     =   6555
   ScaleWidth      =   7965
   StartUpPosition =   3  '窗口缺省
   Begin VB.TextBox Text11 
      Height          =   855
      Left            =   240
      TabIndex        =   22
      Text            =   "拉格朗日：y值"
      Top             =   4440
      Width           =   3855
   End
   Begin VB.TextBox Text10 
      Height          =   855
      Left            =   240
      TabIndex        =   21
      Text            =   "牛顿：y值"
      Top             =   3480
      Width           =   3855
   End
   Begin VB.TextBox Text9 
      Height          =   1095
      Left            =   5640
      TabIndex        =   17
      Text            =   "3"
      Top             =   720
      Width           =   2295
   End
   Begin VB.TextBox Text8 
      Height          =   615
      Left            =   3120
      TabIndex        =   15
      Text            =   "10"
      Top             =   2640
      Width           =   1455
   End
   Begin VB.TextBox Text7 
      Height          =   615
      Left            =   960
      TabIndex        =   13
      Text            =   "6"
      Top             =   2640
      Width           =   1455
   End
   Begin VB.CommandButton Command1 
      Caption         =   "计算对应的y值和公式"
      Height          =   615
      Left            =   360
      TabIndex        =   12
      Top             =   5400
      Width           =   3495
   End
   Begin VB.TextBox Text6 
      Height          =   615
      Left            =   3120
      TabIndex        =   5
      Text            =   "－2"
      Top             =   1800
      Width           =   1455
   End
   Begin VB.TextBox Text5 
      Height          =   615
      Left            =   960
      TabIndex        =   4
      Text            =   "3"
      Top             =   1800
      Width           =   1455
   End
   Begin VB.TextBox Text4 
      Height          =   615
      Left            =   3120
      TabIndex        =   3
      Text            =   "2"
      Top             =   960
      Width           =   1455
   End
   Begin VB.TextBox Text3 
      Height          =   615
      Left            =   960
      TabIndex        =   2
      Text            =   "0"
      Top             =   960
      Width           =   1455
   End
   Begin VB.TextBox Text2 
      Height          =   615
      Left            =   3120
      TabIndex        =   1
      Text            =   "－1"
      Top             =   120
      Width           =   1455
   End
   Begin VB.TextBox Text1 
      Height          =   615
      Left            =   960
      TabIndex        =   0
      Text            =   "－3"
      Top             =   120
      Width           =   1455
   End
   Begin VB.Label Label11 
      Caption         =   "y3"
      Height          =   855
      Left            =   2520
      TabIndex        =   20
      Top             =   2640
      Width           =   615
   End
   Begin VB.Label Label10 
      Caption         =   "x3"
      Height          =   735
      Left            =   360
      TabIndex        =   19
      Top             =   2640
      Width           =   495
   End
   Begin VB.Label Label9 
      Caption         =   "在此输入x值"
      Height          =   1215
      Left            =   5160
      TabIndex        =   18
      Top             =   720
      Width           =   495
   End
   Begin VB.Label Label8 
      Caption         =   "拉格朗日三次对应的y值"
      Height          =   975
      Left            =   4320
      TabIndex        =   16
      Top             =   4440
      Width           =   1335
   End
   Begin VB.Label Label7 
      Caption         =   "牛顿三次插值对应的y值"
      Height          =   855
      Left            =   4440
      TabIndex        =   14
      Top             =   3480
      Width           =   1335
   End
   Begin VB.Label Label6 
      Caption         =   "y2"
      Height          =   495
      Left            =   2520
      TabIndex        =   11
      Top             =   1800
      Width           =   495
   End
   Begin VB.Label Label5 
      Caption         =   "x2"
      Height          =   495
      Left            =   360
      TabIndex        =   10
      Top             =   1920
      Width           =   495
   End
   Begin VB.Label Label4 
      Caption         =   "y1"
      Height          =   495
      Left            =   2640
      TabIndex        =   9
      Top             =   1080
      Width           =   495
   End
   Begin VB.Label Label3 
      Caption         =   "x1"
      Height          =   495
      Left            =   360
      TabIndex        =   8
      Top             =   960
      Width           =   495
   End
   Begin VB.Label Label2 
      Caption         =   "y0"
      Height          =   495
      Left            =   2520
      TabIndex        =   7
      Top             =   240
      Width           =   495
   End
   Begin VB.Label Label1 
      Caption         =   "x0"
      Height          =   495
      Left            =   360
      TabIndex        =   6
      Top             =   240
      Width           =   495
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Private Sub Command1_Click()
Dim x0 As Double
Dim x1 As Double
Dim x2 As Double
Dim x3 As Double

Dim y0 As Double
Dim y1 As Double
Dim y2 As Double
Dim y3 As Double

Dim x As Double
Dim y As Double

Dim t01 As Double
Dim t12 As Double
Dim t23 As Double
Dim t012 As Double
Dim t123 As Double
Dim t0123 As Double

Dim s0 As Double
Dim s1 As Double
Dim s2 As Double
Dim s3 As Double



x0 = Text1.Text
y0 = Text2.Text
x1 = Text3.Text
y1 = Text4.Text
x2 = Text5.Text
y2 = Text6.Text
x3 = Text7.Text
y3 = Text8.Text

x = Text9.Text


t01 = (y0 - y1) / (x0 - x1)
t12 = (y1 - y2) / (x1 - x2)
t23 = (y2 - y3) / (x2 - x3)
t012 = (t01 - t12) / (x0 - x2)
t123 = (t12 - t23) / (x1 - x3)
t0123 = (t012 - t123) / (x0 - x3)
y = y0 + (x - x0) * t01 + (x - x0) * (x - x1) * t012 + (x - x0) * (x - x1) * (x - x2) * t0123

Text10.Text = CStr(y)



s0 = (x - x1) * (x - x2) * (x - x3) / ((x0 - x1) * (x0 - x2) * (x0 - x3))
s1 = (x - x0) * (x - x2) * (x - x3) / ((x1 - x0) * (x1 - x2) * (x1 - x3))
s2 = (x - x0) * (x - x1) * (x - x3) / ((x2 - x0) * (x2 - x1) * (x2 - x3))
s3 = (x - x0) * (x - x1) * (x - x2) / ((x3 - x1) * (x3 - x2) * (x3 - x0))
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y = s0 * y0 + s1 * y1 + s2 * y2 + s3 * y3

Text11.Text = ccstr(y)
End Sub

Function ccstr(a As Double)


  If 0 < a And a < 1 Then ccstr = "0" + CStr(a) '特殊情况 为－1到1 之间的数字
  If -1 < a And a < 0 Then ccstr = "-0" + CStr(Abs(a))
  If CStr(a) = "0" Then ccstr = "0"
  If Abs(a) >= 1 Then ccstr = CStr(a)
      
  End Function