VERSION 5.00
Begin VB.Form Form11 
   BackColor       =   &H00C0C0C0&
   Caption         =   "列主元消去法"
   ClientHeight    =   7770
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   12855
   LinkTopic       =   "Form11"
   ScaleHeight     =   7770
   ScaleWidth      =   12855
   StartUpPosition =   3  '窗口缺省
   Begin VB.PictureBox Picture2 
      BackColor       =   &H00FFFFFF&
      BeginProperty Font 
         Name            =   "宋體"
         Size            =   9
         Charset         =   134
         Weight          =   700
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   5055
      Left            =   5400
      ScaleHeight     =   4995
      ScaleWidth      =   6435
      TabIndex        =   3
      Top             =   2040
      Width           =   6495
   End
   Begin VB.PictureBox Picture1 
      BackColor       =   &H00FFFFFF&
      BeginProperty Font 
         Name            =   "宋體"
         Size            =   9
         Charset         =   134
         Weight          =   700
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   2295
      Left            =   240
      ScaleHeight     =   2235
      ScaleWidth      =   4875
      TabIndex        =   2
      Top             =   2040
      Width           =   4935
   End
   Begin VB.CommandButton Command1 
      Caption         =   "列主元消去法"
      BeginProperty Font 
         Name            =   "宋體"
         Size            =   10.5
         Charset         =   134
         Weight          =   700
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   495
      Left            =   4560
      TabIndex        =   0
      Top             =   480
      Width           =   1695
   End
   Begin VB.Label Label2 
      BackColor       =   &H00C0C0C0&
      Caption         =   "運算結果"
      BeginProperty Font 
         Name            =   "宋體"
         Size            =   10.5
         Charset         =   134
         Weight          =   700
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   495
      Left            =   7560
      TabIndex        =   4
      Top             =   1320
      Width           =   2055
   End
   Begin VB.Label Label1 
      BackColor       =   &H00C0C0C0&
      Caption         =   "方程組的系數矩陣"
      BeginProperty Font 
         Name            =   "宋體"
         Size            =   10.5
         Charset         =   134
         Weight          =   700
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   255
      Left            =   1440
      TabIndex        =   1
      Top             =   1320
      Width           =   2055
   End
End
Attribute VB_Name = "Form11"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Private Sub Command1_Click()
 Dim a(), b(), X() As Single
 'Dim a(3, 3), b(3), X(3) As Single
   Dim i As Integer, j As Integer, k As Integer, n As Integer
   Dim st As String
   'n = 3
   'a(1, 1) = 4: a(1, 2) = -1: a(1, 3) = 1: b(1) = 6
   'a(2, 1) = -1: a(2, 2) = 4.25: a(2, 3) = 2.75: b(2) = -0.5
   'a(3, 1) = 1: a(3, 2) = 2.75: a(3, 3) = 3.5: b(3) = 1.25
    n = InputBox("輸入方程組的個數n", , , 100, 100)
    ReDim X(n), a(n, n), b(n)
    
    Picture1.Cls
  
    For i = 1 To n
       For j = 1 To n
          a(i, j) = InputBox("輸入a(" & i & "," & j & ")的值", , , 100, 100)
          Picture1.Print a(i, j),
       Next j
       
       b(i) = InputBox("輸入b(" & i & ")的值", , , 100, 100)
       Picture1.Print b(i)
       
    Next i
     
    j = 1
    
    k = 1
    While k <= n - 1
                                                   '比高斯消元法多了選主元素
      maxa = Abs(a(k, k))
      m = k
      For i = k To n
         If Abs(a(i, k)) > maxa Then
            maxa = Abs(a(i, k))
            m = i
         End If
      Next i
      If m <> k Then
        For j = k To n
           c = a(k, j)
           a(k, j) = a(m, j)
           a(m, j) = c
        Next j
        c = b(k)
        b(k) = b(m)
        b(m) = c
      End If

       i = k + 1
       While i <= n
          l = a(i, k) / a(k, k)
          j = k
          While j <= n
             a(i, j) = a(i, j) - l * a(k, j)
             j = j + 1
          Wend
          b(i) = b(i) - l * b(k)
          i = i + 1
       Wend
       
       'Picture2.Cls
       Picture2.Print "第" + Str(k) + "次消元后的系數矩陣"
       Picture2.Print
       i = 1
       While i <= n
          j = 1
          While j <= n
             a(i, j) = Int(a(i, j) * 10000) / 10000
             Picture2.Print a(i, j),
             j = j + 1
          Wend
          b(i) = Int(b(i) * 10000) / 10000
          Picture2.Print b(i)
          i = i + 1
       Wend
        Picture2.Print "列主元素為："
        Picture2.Print maxa               '疑問
       ms = MsgBox("按任意鍵繼續")
       k = k + 1
    Wend
    '回代
    b(n) = b(n) / a(n, n)
    X(n) = b(n)
    For i = n - 1 To 1 Step -1
       s = 0
       For j = i + 1 To n
          s = s + a(i, j) * b(j)
       Next j
       b(i) = (b(i) - s) / a(i, i)
       X(i) = b(i)
    Next i
    Picture2.Print
    For i = 1 To n
       Picture2.Print "           x(" + Str(i) + ")=  "; Int(X(i) * 10000) / 10000
    Next i

End Sub