大学里必学的一门课程

VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   5655
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   6360
   LinkTopic       =   "Form1"
   ScaleHeight     =   5655
   ScaleWidth      =   6360
   StartUpPosition =   3  '窗口缺省
   Begin VB.Frame Frame5 
      Caption         =   "公式"
      Height          =   375
      Left            =   2760
      TabIndex        =   11
      Top             =   3120
      Width           =   1335
   End
   Begin VB.Frame Frame4 
      Caption         =   "x"
      Height          =   375
      Left            =   240
      TabIndex        =   10
      Top             =   3360
      Width           =   1215
   End
   Begin VB.Frame Frame3 
      Caption         =   "x1"
      Height          =   375
      Left            =   120
      TabIndex        =   9
      Top             =   1920
      Width           =   1215
   End
   Begin VB.Frame Frame2 
      Caption         =   "x0"
      Height          =   375
      Left            =   120
      TabIndex        =   8
      Top             =   480
      Width           =   975
   End
   Begin VB.Frame Frame1 
      Caption         =   "值"
      Height          =   375
      Left            =   2760
      TabIndex        =   7
      Top             =   1320
      Width           =   1095
   End
   Begin VB.TextBox Text5 
      Height          =   855
      Left            =   2760
      TabIndex        =   6
      Top             =   1680
      Width           =   2415
   End
   Begin VB.TextBox Text4 
      Height          =   855
      Left            =   2760
      TabIndex        =   5
      Top             =   3480
      Width           =   2175
   End
   Begin VB.CommandButton Command2 
      Caption         =   " 公式"
      Height          =   495
      Left            =   5160
      TabIndex        =   4
      Top             =   3600
      Width           =   1215
   End
   Begin VB.TextBox Text3 
      Height          =   615
      Left            =   240
      TabIndex        =   3
      Top             =   3720
      Width           =   1815
   End
   Begin VB.TextBox Text2 
      Height          =   615
      Left            =   120
      TabIndex        =   2
      Top             =   2280
      Width           =   1815
   End
   Begin VB.TextBox Text1 
      Height          =   615
      Left            =   120
      TabIndex        =   1
      Top             =   840
      Width           =   1815
   End
   Begin VB.CommandButton Command1 
      Caption         =   "计算"
      Height          =   495
      Left            =   5280
      TabIndex        =   0
      Top             =   1800
      Width           =   1095
   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 t0 As Double
Dim t1 As Double


Dim y0 As Double
Dim y1 As Double
Dim y  As Double

x0 = Text1.Text
x1 = Text2.Text
x = Text3.Text
y0 = Exp(-x0)
y1 = Exp(-x1)

t0 = (x - x1) / (x0 - x1)
t1 = (x - x0) / (x1 - x0)

y = t0 * y0 + t1 * y1
Text5.Text = ccstr(y)


End Sub

Private Sub Command2_Click()
Dim x0 As Double
Dim x1 As Double
Dim y0 As Double
Dim y1 As Double

Dim t0 As String
Dim t1 As String



x0 = Text1.Text
x1 = Text2.Text
y0 = Exp(-x0)
y1 = Exp(-x1)

t0 = "(x-" + ccstr(x1) + ")/" + ccstr((x0 - x1))
t1 = "(x-" + ccstr(x0) + ")/" + ccstr((x1 - x0))
y = "(" + t0 + ")" + "*" + ccstr(y0) + "+" + "(" + t1 + ")" + "*" + ccstr(y1)
Text4.Text = 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