form1.frm

可求标准正太累计分布函数

VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   3090
   ClientLeft      =   60
   ClientTop       =   450
   ClientWidth     =   4680
   LinkTopic       =   "Form1"
   ScaleHeight     =   3090
   ScaleWidth      =   4680
   StartUpPosition =   3  '窗口缺省
   Begin VB.TextBox Text4 
      Height          =   375
      Left            =   720
      TabIndex        =   8
      Text            =   "0.5"
      Top             =   240
      Width           =   855
   End
   Begin VB.TextBox Text3 
      Height          =   495
      Left            =   2880
      TabIndex        =   6
      Text            =   "输出结果"
      Top             =   2040
      Width           =   1455
   End
   Begin VB.TextBox Text2 
      Height          =   495
      Left            =   2880
      TabIndex        =   3
      Text            =   "497"
      Top             =   1080
      Width           =   1455
   End
   Begin VB.CommandButton Command1 
      Caption         =   "计算"
      Height          =   375
      Left            =   3600
      TabIndex        =   2
      Top             =   2640
      Width           =   855
   End
   Begin VB.TextBox Text1 
      Height          =   375
      Left            =   2880
      TabIndex        =   0
      Text            =   "746"
      Top             =   240
      Width           =   1455
   End
   Begin VB.Label Label4 
      Caption         =   "电压变化步长"
      Height          =   375
      Left            =   120
      TabIndex        =   7
      Top             =   120
      Width           =   615
   End
   Begin VB.Label Label3 
      Caption         =   "带电作业危险率"
      Height          =   495
      Left            =   1800
      TabIndex        =   5
      Top             =   2040
      Width           =   975
   End
   Begin VB.Label Label2 
      Caption         =   "Ua 操作过电压平均值"
      Height          =   495
      Left            =   1800
      TabIndex        =   4
      Top             =   1080
      Width           =   975
   End
   Begin VB.Label Label1 
      Caption         =   "U50%放电电压"
      Height          =   615
      Left            =   1800
      TabIndex        =   1
      Top             =   120
      Width           =   975
   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 Ustart1, USTART2, U, Ustep As Double
Dim R2 As Double
Ustart1 = Text1.Text
USTART2 = Text2.Text
Ustep = Text4.Text
U = Text1.Text
R2 = 0
Do While (U - Ustart1) / Ustart1 / 0.03 < 10
R2 = (2 - NormSDist((U - Ustart1) / Ustart1 / 0.03) - NormSDist((U + Ustep - Ustart1) / Ustart1 / 0.03)) / 2 * (NormSDist((U + Ustep - USTART2) / USTART2 / 0.12) - NormSDist((U - USTART2) / USTART2 / 0.12)) + R2
U = U + Ustep
Loop
Text3.Text = R2
End Sub

Private Function NormSDist(z As Double) As Double
Dim step1 As Double
Dim pi As Double
step1 = 0.001
r1 = 0
pi = 3.1415926
For i = -20 To z Step step1
r1 = 1 / (2 * pi) ^ (1 / 2) * (Exp(-(i) ^ 2 / 2) + Exp(-(i + step1) ^ 2 / 2)) / 2 * step1 + r1
Next
NormSDist = r1
End Function