使用句点值迭代日期范围内的值，以及如何将其用作公式

Question

I have few start/end dates, few prices per month, and table with dates and course for that dates one per month, so i need to iterate over course values depending on how long period between two dates, I think alot about standard formulas nothing is matches, so I try to put my PHP knowledge, learn suntax and write my first vba code, I place it here:

http://pastebin.com/XXLKvdA4

excel data mean table of contents looks like this:

  [startDate]| [endDate]  |[inMonth]|           [totalByCourse]
  11.01.2010 | 20.02.2011 |   200   | =ConvertCourse( A1, B1, C1, myRange )
  15.05.2010 | 25.03.2011 |   400   | =ConvertCourse( A2, B2, C2, myRange )

... so on for about 100 times

#     [date]   |[course]
1   30.08.2010 |   5
    ...
5   30.12.2010 |   18
6   10.01.2011 |   2
    ...
10  10.05.2011 |   6
... so on for about 20 times

The range of date | course presented to macro is named as myRange it isn't begins from first month of year and not ends as last month of year so it make some lot's complexity to calc algorithm, and made me to write some bruteforce loops, thats why code have many if check statenements.

Excel compiler crushes at first line of ConvertCourse function call and tell nothing more than the comments is may appear etc, its also write strange output directly to module like

ActiveCell.FormulaR1C1 = _
        "=ConvertCourse(R[-1]C[-6],RC[-5],R[-1]C[-3],CourseRange)"
    Range("K3").Select

I just want to use it as formula withour output to modules with functions, whats wrong with call and how to do it right?

Answer 1

The function takes the [totalByCourse] / 30 and multiplies it by the [Course] cost for each month between two dates while adjusting the cost for a short month.

I recommend replicating the function with built-in Excel WorkSheet functions. I could not do it without complete sample data and the actual expected results to compare the output.

Two new named ranges are hard coded into the formula.

CourseDates =OFFSET( Sheet1!$H$1,1,0,COUNTA(Sheet1!$H:$H)-1,1)

Courses =OFFSET(Sheet1!$I$1,1,0,COUNTA(Sheet1!$I:$I)-1,1)

Formula

SUMPRODUCT(--(CourseDates>=--"2011-07-20"),--(CourseDates<=--"2011-8-20"),Courses*DailyCost)

Function ConvertCourse(StartDate As Date, EndDate As Date, pSumMonthly As Double) As Double
    Const dLength As Integer = 30
    Dim x As Long
    Dim periodInDays As Integer, DailyCost As Double, result As Double
    Dim NewEndDate As Date

    DailyCost = pSumMonthly / dLength
    periodInDays = DateDiff("d", StartDate, EndDate)
    NewEndDate = StartDate + Int(periodInDays / dLength) * 30

    result = getCourseTotal(StartDate, NewEndDate, DailyCost)

    If NewEndDate < EndDate Then

        result = result + (EndDate - NewEndDate) * DailyCost * getCourseTotal(StartDate, NewEndDate, 1)

    End If

    ConvertCourse = result

End Function

'SUMPRODUCT(--(CourseDates>=--"2011-07-20"),--(CourseDates<=--"2011-8-20"),Courses*130)
Function getCourseTotal(StartDate As Date, EndDate As Date, DailyCost As Double)
    Dim Formula As String
    Formula = "=SUMPRODUCT(--(CourseDates>=--" & Format(StartDate, "\""YYYY-MM-DD\""") & _
              "),--(CourseDates<=--" & Format(EndDate, "\""YYYY-MM-DD\""") & "),Courses)"

    getCourseTotal = Evaluate(Formula) * DailyCost
End Function