用迭代法求x=a^1/3求立方根的迭代公式为：xi+1=2/3xi+a/(3xi^2)迭代到xi+1-xi的绝

Question

用迭代法求x=a^1/3求立方根的迭代公式为：xi+1=2/3xi+a/(3xi^2)迭代到xi+1-xi的绝

Answer 1

Private Sub Command1_Click()
Dim x As Single,x0 As Single,x1 As Single,a As Single
a = Val(InputBox("请输入一个数a="))
If Abs(a) < 0.000001 Then
x = 0
Else
x0 = a / 2
x1 = (2 / 3 * x0) + a / (3 * x0 ^ 2)
Do While Abs(x1 - x0) > 0.00001
x0 = x1
x1 = (2 / 3 * x0) + a / (3 * x0 ^ 2)
Loop
x = x1
End If
Print a & "的立方根为;"; x
End Sub