用VB计算圆周率,步骤写清楚精确到1000位采用普遍的傅立叶级数展开方法pi=2+1/3*(2+2/5*(2+3/7*(2+4/9*(2+5/11.))))))

Question

用VB计算圆周率,步骤写清楚精确到1000位
采用普遍的傅立叶级数展开方法 pi=2+1/3*(2+2/5*(2+3/7*(2+4/9*(2+5/11 .))))))

Answer 1

Private Sub Command1_Click()
getpi 1000
End Sub

Sub getpi(Optional ByVal nums As Long = 10000)
nums = nums / 5
Dim max As Long, laptime As Single, result() As String
Dim i, j As Long, d As Long, t, g, r, k As Long, f()
laptime = Timer
max = 10 * nums
ReDim f(1 To max)
ReDim result(nums)
result(0) = vbCrLf
For i = 1 To max
f(i) = 30000
Next
For j = max To 1 Step -10
t = 0
For i = j To 1 Step -1
If j = max Then
t = t + f(i) * 1000000
Else
t = t + f(i) * 100000
End If
r = 8 * i * (2 * i + 1)
f(i) = t - Int(t / r) * r
d = 2 * i - 1
t = Int(t / r) * d * d
Next
k = k + 1
result(k) = Format(Int(g + t / 100000) Mod 100000, "00000")
If k Mod 20 = 0 Then result(k) = result(k) & vbCrLf
If k Mod 200 = 0 Then result(k) = result(k) & "---[" & k * 5 & "]---" & vbCrLf
g = t Mod 100000
Next
Text1.Text = Join(result, " ")
Me.Caption = "计算完毕!总计用时" & Timer - laptime & "秒!"
End Sub