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Converting VBA to Fortran

  1. Nov 18, 2011 #1
    Hi, I've no knowledge of Fortran but am researching its (theoretical) use to perform a 'cross- referencing' function on data in a four column array of one million rows. The program matches data in column A to Column D by referencing the matching values in columns B and C.

    Here's the program I'm using - could anyone convert this to Fortran and could this in, in practice, run on Fujitsu's K (10 teraflops) computer. If so, how long would it take the K to perform this task - I've calculated 12.93 hrs from tests on a typical office PC? With thanks.

    Sub AddCodes()

    Dim x As Long, LastRow As Long, UB As Long, BList As Variant

    Const StartRow As Long = 1
    LastRow = Cells(Rows.Count, "A").End(xlUp).Row

    BList = Join(WorksheetFunction.Transpose(Cells(StartRow, "B").Resize(LastRow - StartRow + 1)), "/")
    ' Application.ScreenUpdating = False

    For x = StartRow To LastRow
    UB = UBound(Split(Split(BList, Cells(x, "C").Value)(0), "/"))
    If UB >= 0 Then
    With Cells(x, "D")
    .Value = .Value & "," & Range("A1").Offset(UB).Value
    If Left(.Value, 1) = "," Then .Value = Mid(.Value, 2)
    .Interior.ColorIndex = 6
    .Font.Bold = True
    End With
    End If
    Next

    Application.ScreenUpdating = True

    End With

    End Sub
     
  2. jcsd
  3. Nov 18, 2011 #2

    AlephZero

    User Avatar
    Science Advisor
    Homework Helper

    If it takes 12 hours on a PC your algorithm is hopelessly inefficient.

    If you first sorted the table on the relevant columns and then did the matching, I would expect the run time to be of the order of 1 second not 12 hours.

    Relational database operations are a good way to describe what you want to do, but they are often a bad way to actually do it.
     
  4. Nov 21, 2011 #3
    Many thanks for your answer - your advice made me re-think the code and I've processed the array with vlookup instead and yes, you're right of course, about a second!

    However, I'm still interested to knnow how my original code qwould translate into Fortran.

    Thanks once again!
     
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