公式：预测值＝aX（上一期的实际值）＋（1－a)X（上一期的预测值）
而第一期预测值=所有期数值的平均数
Private Sub Command1_Click()
Dim x() As Single
Dim y As Single
Dim a As Single
Dim sumx As Single
Dim n, i As Integer
a = Val(Text1.Text)
n = InputBox("请输入您要输入数据的个数")
ReDim x(n)
ReDim q(0 To n), s(0 To n) As Double
For i = 0 To n - 1
x(i) = InputBox("请输入第" + Str(i + 1) + "个x的值")
sumx = sumx + x(i)
Next i
q(1) = sumx / n
s(1) = q(1)
’从这里开始就有问题！x（i）值那些算出来都有问题。
For i = 2 To n
q(i) = a * x(i - 1) + (1 - a) * q(i - 1)
Next i
y = a * x(n) + (1 - a) * q(n)
Text2.Text = y
End Sub