最近在学习这本书，里面有一些程序自己不是太明白，例如书中4.7的配套程序：
Function ZNplotmat(dvec)
'   Returns data matrix (nx2) for normal probability plot
    Dim M, V
    Dim i As Integer, n As Integer, r As Integer
    Dim znmat() As Variant
    n = Application.Count(dvec)
    ReDim znmat(n, 2)
    M = Application.Average(dvec)
    V = Application.Var(dvec)
    For i = 1 To n
        znmat(i, 1) = (dvec(i) - M) / Sqr(V)
        r = Application.Rank(dvec(i), dvec, 1)
        znmat(i, 2) = Application.NormSInv((r - 3 / 8) / (n + 1 / 4))
   Next i
    ZNplotmat = znmat
End Function
想请问一下FOR循环语句中程序的意图？标红部分更是一头雾水！