This is the full text of a program that converts a decimal number to a
fraction, and handles repeating decimals correctly, including the case
where there is a portion of the fractional part that is non-recurring. I
have almost followed the form layout in your example, although two extra
text boxes are required to demonstrate the parameters used for the
recurring decimal case - you could simply make these internal variables
instead of text box values.
It is set up to test using manually entered numbers, for reasons that
become clear below.
For instance:
1.25 1 1 4
5.75 5 3 4
1.3 1 3 10
1.33 1 1 3
1.7272 1 8 11
0.8666 0 13 15
1.31999 1 8 25
Note that the repeating test is not foolproof - for instance it will
detect the repeating part of 1.25252 as 52, which might not be what was
intended. The cases where it fails are ambiguous, and I don't think there
is any way around the issue without some very arbitrary decisions or
asking the operator to indicate exactly what the recurring part is. This
also means it will NOT work properly with decimal numbers created from a
fraction, because the computer will usually round the last digit. So
1.66667 will not be detected as repeating. This is the problem with your
original test procedure - you were producing decimal numbers from a
fraction, but those numbers could not be expressed in the machine as a
proper repeating decimal, so they would never be converted back to the
same fraction, however good your conversion was.
Imports System.Text.RegularExpressions
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click
Dim s() As String
Dim value As Double, numer As Double, denom As Double
Dim repeats As Double, startat As Double
TxtRepeats.Text = "0"
TxtStartAt.Text = "0"
If InStr(txtWhole.Text, ".") = 0 Then Beep() : Exit Sub
s = Split(txtWhole.Text, ".")
If s(0) = "" Then Beep() : Exit Sub
If s(1) = "" Then Beep() : Exit Sub
CheckRepeating(s(1))
value = Val(txtWhole.Text)
repeats = Val(TxtRepeats.Text) 'Number of digits per repeat
sequence
startat = Val(TxtStartAt.Text) 'Position (base 1) of first digit in
first repeat seq.
startat -= 1
If startat <= 0 Then startat = repeats
If repeats = 0 Then
denom = 10 ^ Len(s(1))
numer = Val(txtWhole.Text) * denom
Else
Dim Q As String = s(1).Substring(0, startat)
Dim R As String = s(1).Substring(startat)
Dim Q1 As Integer = Val(Q & R.Substring(0, repeats)) - Val(Q)
denom = Val(StrDup(CInt(repeats), "9") & StrDup(Q.Length, "0"))
numer = Q1 + Val(s(0)) * denom
End If
txtNumer.Text = numer.ToString
txtDenom.Text = denom.ToString
Me.Refresh()
Simplify()
End Sub
Sub CheckRepeating(ByVal s As String)
Dim MyRegex As Regex = New Regex("(\d+)\1{1,}\z")
If Not MyRegex.IsMatch(s) Then Exit Sub
Dim ms As MatchCollection = MyRegex.Matches(s)
Dim m As String = ms.Item(ms.Count - 1).Groups("1").Value
TxtRepeats.Text = m.Length
TxtStartAt.Text = InStr(s, m)
End Sub
Private Sub Simplify()
Dim n As Long = Val(txtNumer.Text)
Dim d As Long = Val(txtDenom.Text)
Dim i As Long
For i = n To 1 Step -1
If (n / i = Int(n / i)) And (d / i = Int(d / i)) Then Exit For
Next
n = n / i
d = d / i
i = 0
If d > 0 Then
While n > d
i = i + 1 : n = n - d
End While
End If
TxtResultW.Text = i.ToString
TxtResultN.Text = n.ToString
TxtResultD.Text = d.ToString
End Sub
End Class
Kasha said:
I AM using three text boxes =] , one for the whole number, one for the
numerator, and one for the denomenator.
Dim denomtest As Integer
Dim numertest As Integer
Dim dota As Boolean
Dim dotb As Boolean
Dim time As Integer = 1
Dim num As Integer = 2
Dim numertesthold As Integer
Dim denomtesthold As Integer
Dim numertesta As Integer
Dim denomtesta As Integer
Dim frac As Double
Dim i As Integer
Private Sub convert()
IF int(numer.Text) = 66 THEN
numertest = 1
denomtest = 6
Goto chocolate cake
Endif
time = 1
denomtesthold = denom.Text
numertesthold = numer.Text
top:
Do Until time = 100
For num = 2 To 51
If num = 51 Then GoTo chocolate
numertesta = numertesthold
denomtesta = denomtesthold
numertest = numertesta / num
denomtest = denomtesta / num
For i = 2 To Len(numertest)
If dota = True Or dota = False Then GoTo Here
If Mid(numertest, i, 1) = "." Then dota = True
If i = Len(numertest) Then dota = False
Next
Here:
For i = 2 To Len(denomtest)
If dotb = True Or dotb = False Then GoTo There
If Mid(denomtest, i, 1) = "." Then dotb = True
If i = Len(denomtest) Then dotb = False
Next
There:
If dota = False And dotb = False And denomtest <> 0 And
numertest <> 0 And numertest / denomtest = frac Then
i = 2
time = time + 1
denomtesthold = denomtest
numertesthold = numertest
GoTo top
End If
Next
Loop
chocolate:
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click
Whole.Text = Int(Inch.Text)
numer.Text = (Inch.Text - whole.Text) * 10000000
denom.Text = 10000000
frac = numer.Text / denom.Text
Call convert()
Whole.Text = Int(Inch.Text)
Numer.Text = numertesthold
Denom.Text = denomtesthold
End Sub
End Class
That's how far I currently am. If I were to use your code, where would I
place it?
James Hahn said:
Firstly, you can present the results from the three text boxes as a
string:
text1.text & " " & text2.text & "/" & Text3.text
Secondly, any repeating decimal can be represented as the correct
fraction using code, but you haven't indicated what your problem with
this procedure is.
How is the user indicating that the decimal number is repeating
indefinately, or is the problem that you can't detect when it's a
repeating decimal? This could probably be solved with a regular
expression.
Or is the problem that you don't know how to reduce a regular repeating
number to a fraction? This is relatively easy, once you know the
characteristics. For instance, if its a simple set of repeating digits,
just use:
(Repeats is the number of digits that are repeated, textbox1 has the
number to convert)
s = Split(TextBox1.Text, ".")
s(0) = s(0) & s(1).Substring(0, repeats)
numerator = Val(s(0) & "." & s(1))
power = 10 ^ repeats
numerator = numerator - value
denominator = power - 1
then simplify if possible. If it's some unique digitis followed by a
repeating portion you need to allow for that in the adjustment of the
value, and then adjust the numerator and denominator by powers of 10
until you have eliminated the fractional part of the numerator.
The goal of the program is to convert decimals to fractions with only
the input of a decimal number, and thus far, I've only been able to
simplify nonrepeating decimal numbers. If I were to have the user
specify the finest graduation, I'd need a drastically different code,
and I'd be going beyond the goal of the program =\
Is my goal hopeless without specifying the finest graduation then?
-Jason
Jason, if you can have your users specify the finest graduation to
output (say, 64ths, 8ths, quarters, etc.), or if you assume a certain
finest graduation, you can convert a repeating fraction and then round
to the finest graduation that the number converts to, and then reduce
it if possible.
So for instance, your 1/3 is 0.33333... If your finest graduation is
128ths, multiply the 0.33333... by 128, getting 42.66666... and round
to 43, giving youi 43 / 128ths.
Similarly, 1/9 is 0.11111... For 128ths, multiply 0.11111... by 128,
getting 14.22222... Round to 14/128ths and reduce to 7/64ths.
Tom Dacon
Dacon Software Consulting
I'm making a program that will convert decimal inputs (in this case,
in inches) and output a fractional answer. At the moment, I'm only
able to output the fractional answer in three parts: A whole number
text box, a numerator text box, and a denominator text box. I
realize that this is probably the closest I'll get to having
fractions displayed in VB, so that's no big deal. I'm able to
simplify most numbers with some code I've written, but I'm unable to
simplify anything that repeats infinitely (i.e.. 1/3). Is there any
way to be able to simplify this?
I can give you the code I've already written if that would help.
Thanks!
