Calculating Day of Week Given MM-DD-YYYY

[eyeRmonkey]

Okay, I have spent a lot of time simplifying this formula. I attached an image of the new version. This is actually the 3rd revision I have made. The last one I didn't post because it was only slightly nicer than the one above.

Here is the code in VB.

Private Function ConvertToDayOfWeek3( _
        ByVal M As Long, _
        ByVal D As Long, _
        ByVal Y As Long _
    ) As Long
    Dim lReturn             As Long
    Dim lYearStart          As Long
    Dim lMonthOffset        As Long
    Dim lDay                As Long
    Dim lLeapYearAfterFeb   As Long
    
    lYearStart = Int(365.25 * (Y - 1))
    lMonthOffset = Int(530526416330# / 10 ^ (M - 1)) - Int(530526416330# / 10 ^ M) * (10)
    lLeapYearAfterFeb = (1 - Int((Y Mod 4) / (Y Mod 4 - 0.01))) * Int(Int(M / 3) / (Int(M / 3) - 0.0001))
    lDay = D - 1
    
    lReturn = (lYearStart + lMonthOffset + lDay + lLeapYearAfterFeb) Mod 7
    
    ConvertToDayOfWeek3 = lReturn
End Function