牛顿插值源代码.txt

用vb实现牛顿插值

Dim x(3), y(3, 3) As Single
Const n = 3



Private Sub Command1_Click()
Text1.Text = ""
Dim s As Single
xl = Text2.Text
For j = 1 To n
    For i = j To n
        y(i, j) = (y(i, j - 1) - y(i - 1, j - 1)) / (x(i) - x(i - j))
    Next i
Next j
If Text2.Text = "" Then
MsgBox ("请输入插入数值！")
Else


s = y(0, 0) + y(1, 1) * (xl - x(0)) + y(2, 2) * (xl - x(0)) * (xl - x(1)) + y(3, 3) * (xl - x(0)) * (xl - x(1)) * (xl - x(2))
Label3.Caption = "f(" & Text2.Text & ")=" & Format(s, "##0.00000")
For i = 0 To n
     
    
    Text1.Text = Text1.Text & vbCrLf & Space(5) & Format(x(i), "###0.00000") & Space(3) & Format(y(i, 0), "###0.00000") & Space(5) & Format(y(i, 1), "###0.00000") & Space(8) & Format(y(i, 2), "###0.00000") & Space(8) & Format(y(i, 3), "####.00000")
    
    
Next i
End If


End Sub

Private Sub Form_Load()
form1.Show
'n = Val(InputBox("请输入插值次数n：", "系统提示"))
'ReDim x(n)
'ReDim y(n, n)
For i = 0 To n
    For j = 0 To n
        y(i, j) = 0
    Next j
Next i
x(0) = 1.275
x(1) = 1.1503
x(2) = 1.1735
x(3) = 1.1972
y(0, 0) = 0.1191
y(1, 0) = 0.13954
y(2, 0) = 0.15932
y(3, 0) = 0.17903
Text1.Text = Space(8) & "x" & Space(8) & "y" & Space(8) & "一阶差商" & Space(8) & "二阶差商" & Space(8) & "三阶差商"
End Sub