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Thread: Implementing formulas with variables into VBA

  1. #1

    Implementing formulas with variables into VBA

    Hi I'm new to VBA.
    I'm struggling to write a script for an equation with several variables.
    Mathematically the equation is written in the form:
    X/L = AuU* ((1-e)2 (1+30(1-f)3 ) / d2 )
    I am attempting to add the variables (letters) and the overall relationship so that it can be graphed.
    Any pointers, insight or help would be appreciated.
    Thanks,
    ITY

  2. #2
    X/L = AuU* ((1-e)2 (1+30(1-f)3 ) / d2 )

    It's really hard to tell what are the independent variables and the independent one

    Assuming that

    1. X/L is a single number (just written wrong for VBA)
    2. AuU is a single number and not Au times U
    3. (1-e)2 means (1-e) squared
    4. (1-f)3 means (1-f) cubed
    5. d2 means d squared

    then a user defined function (UDF) in the workbook would be one way (below). The other would just be a long worksheet formula

     
    Option Explicit 
     
    Function XoverL(AuU As Double, e As Double, f As Double, d As Double) As Double 
        XoverL = AuU * ((1 - e) ^ 2 * (1 + 30 * (1 - f) ^ 3) / d ^ 2) 
    End Function 
     
     
    Sub test() 
        MsgBox XoverL(100, 0.5, 12, 9) 
    End Sub 
    
    
    Formatting tags added by mark007

    It's be a lot easier of offer suggestions if you attach a sample workbook with some dummy (but realistic) data (see my sig)
    Paul

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  3. #3
    Moderator VBAX Wizard SamT's Avatar
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    Assuming that "X" is the column you want the results in, and "A" is the column with AuU in, "E" has e in, "F" has f, and "D" has d
     'Standard Module Code.
    Option Explicit 
     
    Public Function XoverL(AuU As Range, e As Range, f As Range, d As Range) As Double 
        XoverL = AuU * ((1 - e) ^ 2 * (1 + 30 * (1 - f) ^ 3) / d ^ 2) 
    End Function 
    
    
    Formatting tags added by mark007
    In Column X, the Formula is "=XoverL(AU,E,F,D)

    Copy that formula down to the bottom of the table .Edit the letters in the Cell Formula to represent the actual Column Letters the Values are really in and place the cell formula in the appropriate Results column.
    Please take the time to read the Forum FAQ

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