我正在尝试使用Excel VB实现一个简单的牛顿方法迭代求解器(我从未使用过VB.)
我一直收到错误loop without a Do
,我无法弄清楚我在这里做错了什么.
我试图找到z^3 - z^2 - (B^2 + B - A)z - A*B
称为压缩因子的函数的根.
我的来源MSN
Function zCalculation(ByVal temp As Double, ByVal press As Double) As Double Dim tempCr As Double Dim pressCr As Double Dim A As Double Dim B As Double tempCr = temp / 238.5 pressCr = press / 547.424092 A = pressCr / tempCr A = A / (9 * (2 ^ (1 / 3) - 1)) B = pressCr / tempCr B = B * (2 ^ (1 / 3) - 1) / 3 Dim zNot As Double Dim counter As Integer counter = 0 zNot = 1# Do counter = counter + 1 zNot = zNot - (zNot ^ 3 - zNot ^ 2 - (B ^ 2 + B - A) * zNot - A * B) / (3 * zNot ^ 2 - 2 * zNot - (B ^ 2 + B - A)) If counter > 1000 Then Exit Do Loop Until eval(zNot, A, B) < 0.000001 zCalculation = zNot End Function
打破
Function eval(ByVal z As Double, ByVal A As Double, ByVal B As Double) As Double eval = z ^ 3 - z ^ 2 - (B ^ 2 + B - A) * z - A * B End Function
Gary's Stude.. 18
你需要一个:
End If
在你的代码中.