modnh.bas

用于空间插值的地理数据处理的趋势面分析

Attribute VB_Name = "ModNH"
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'模块名：ModNH
'函数名：NHDC
'功能：检验趋势面的拟合程度
'参数：n－integer型变量，观测点数
        'a()－double型变量，观测点X坐标
        'b()－double型变量，观测点Y坐标
        'c()－double型变量，观测点数值
'返回值：NHDC－double型变量，拟合度C值，当C大于95％，认为拟合度满足要求
        
Public Function NHDC(ByVal n As Double, a() As Double, b() As Double, c() As Double) As Double
    Dim Stotal As Double
    Dim C1 As Double
    Dim i As Integer
    Dim Zk() As Double               '趋势值
    Dim Z1 As Double                 '平均值
    
    ReDim Zk(1 To n)
    
    For i = 1 To n
        Z1 = Z1 + c(i)
        Zk(i) = ZX(a(i), b(i))
    Next
    Z1 = Z1 / n
    
    For i = 1 To n
        Sresidual = Sresidual + (c(i) - Zk(i)) ^ 2
        Sregress = Sregress + (Zk(i) - Z1) ^ 2
    Next
    
    Stotal = Sregress + Sresidual
    NHDC = (Sregress / Stotal) * 100
End Function