主题：[求助]列内容变化后计算

Dim strs As List(Of String) = DataTables("产品").GetValues("名称")

For Each str As String In strs
    Dim drs As List(Of DataRow) = DataTables("产品").Select("名称 = '" & str & "'", "时间")

    if drs.count > 0 then
    Dim dr1 As DataRow = drs(0)
    dr1("距离累加值") = 0
    For i As Integer = 1 To drs.Count - 1
        Dim x1 As Double = drs(i-1)("纬度")
        Dim y1 As Double = drs(i-1)("经度")
        Dim x2 As Double = drs(i)("纬度")
        Dim y2 As Double = drs(i)("经度")
        
        Dim rad As Double = 6371
        Dim p1X As Double = X1 / 180 * Math.PI
        Dim p1Y As Double = Y2 / 180 * Math.PI
        Dim p2X As Double = X2 / 180 * Math.PI
        Dim p2Y As Double = Y2 / 180 * Math.PI
        Dim result As Double = Math.Acos(Math.Sin(p1Y) * Math.Sin(p2Y) + Math.Cos(p1Y) * Math.Cos(p2Y) * Math.Cos(p2X - p1X)) * rad
        drs(i)("距离累加值") = drs(i-1)("距离累加值") + result

Next

end if