Simplify Fraction UDF Error

[Juggler_IN]

I have a Simply Fraction UDF which works fine whenever the numerator is less than the denominator, but fails other wise. For example for n = 50, d = 75 it outputs 2/3 but for n = 5 , d = 4 it is failing. Any reason?

Private Function reduceFraction(n As Integer, d As Integer)
    Dim numL As Variant
    Dim numR As Variant
    Dim i As Integer


    'check for both negative
    If n < 0 And d < 0 Then
        n = -1 * n: d = -1 * d
    End If
    'take out the whole number
    whole = Fix(n / d)


    'numL = IIf(whole > 0, Trim(whole) & " ", "")


    'set n to the remainder
    n = n Mod d
    MsgBox Abs(n)
    For i = Abs(n) To 2 Step -1
        If n / i = Fix(n / i) And d / i = Fix(d / i) Then
            numL = IIf(whole > 0, Trim(whole) & " ", "")
            'Debug.Print numL
            numR = Trim(n / i) & "/" & Trim(d / i)
            'Debug.Print numR
            reduceFraction = numL & numR
            Exit For
        End If
    Next i


End Function

 

[jmacleary]

The problem lies in the MOD function. There are several warnings about how MOD doesn't always do the right thing, see here as an example. https://stackoverflow.com/questions/4378047/vba-equivalent-to-excels-mod-function

 

[Eric W]

You might also consider the GCD function. You can come up with a more efficient function, such as:

Private Function ReduceFrac(n As Integer, d As Integer)
Dim g as Integer

    If n < 0 And d < 0 Then
        n = -n
        d = -d
    End If
    
    g = WorksheetFunction.Gcd(Abs(n), Abs(d))
    ReduceFrac = n / g & " / " & d / g
    
End Function

 

[DanteAmor]

Change this line

For i = Abs(n) To [SIZE=3][B][COLOR=#ff0000]1[/COLOR][/B][/SIZE] Step -1

 

[Juggler_IN]

@DanteAmor; it works

 

[Juggler_IN]

@Eric W; the HCF approach works well.

 

[DanteAmor]

@DanteAmor; it works

I'm glad to help you. Thanks for the feedback.