Fractran: Difference between revisions
→{{header|VBA}}
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</pre>
=={{header|VBA}}==
This implementations follows the Wikipedia description of [[wp:FRACTRAN|FRACTRAN]]. There are test, decrement and increment instructions on an array of variables which are the exponents of the prime factors of the argument, which are the only instructions used to run the program with the function run, or go through it step by step with the function steps. An auxiliary factor function is used to compile the FRACTRAN program.
<lang vb>Option Base 1
Public prime As Variant
Public nf As New Collection
Public df As New Collection
Const halt = 20
Private Sub init()
prime = [{2,3,5,7,11,13,17,19,23,29,31}]
End Sub
Private Function factor(f As Long) As Variant
Dim result(10) As Integer
Dim i As Integer: i = 1
Do While f > 1
Do While f Mod prime(i) = 0
f = f \ prime(i)
result(i) = result(i) + 1
Loop
i = i + 1
Loop
factor = result
End Function
Private Function decrement(ByVal a As Variant, b As Variant) As Variant
For i = LBound(a) To UBound(a)
a(i) = a(i) - b(i)
Next i
decrement = a
End Function
Private Function increment(ByVal a As Variant, b As Variant) As Variant
For i = LBound(a) To UBound(a)
a(i) = a(i) + b(i)
Next i
increment = a
End Function
Private Function test(a As Variant, b As Variant)
flag = True
For i = LBound(a) To UBound(a)
If a(i) < b(i) Then
flag = False
Exit For
End If
Next i
test = flag
End Function
Private Function unfactor(x As Variant) As Long
result = 1
For i = LBound(x) To UBound(x)
result = result * prime(i) ^ x(i)
Next i
unfactor = result
End Function
Private Sub compile(program As String)
program = Replace(program, " ", "")
programlist = Split(program, ",")
For Each instruction In programlist
parts = Split(instruction, "/")
nf.Add factor(Val(parts(0)))
df.Add factor(Val(parts(1)))
Next instruction
End Sub
Private Function run(x As Long) As Variant
n = factor(x)
counter = 0
Do While True
For i = 1 To df.Count
If test(n, df(i)) Then
n = increment(decrement(n, df(i)), nf(i))
Exit For
End If
Next i
Debug.Print unfactor(n);
counter = counter + 1
If num = 31 Or counter >= halt Then Exit Do
Loop
Debug.Print
run = n
End Function
Private Function steps(x As Variant) As Variant
'expects x=factor(n)
For i = 1 To df.Count
If test(x, df(i)) Then
x = increment(decrement(x, df(i)), nf(i))
Exit For
End If
Next i
steps = x
End Function
Private Function is_power_of_2(x As Variant) As Boolean
flag = True
For i = LBound(x) + 1 To UBound(x)
If x(i) > 0 Then
flag = False
Exit For
End If
Next i
is_power_of_2 = flag
End Function
Private Function filter_primes(x As Long, max As Integer) As Long
n = factor(x)
i = 0: iterations = 0
Do While i < max
If is_power_of_2(steps(n)) Then
Debug.Print n(1);
i = i + 1
End If
iterations = iterations + 1
Loop
Debug.Print
filter_primes = iterations
End Function
Public Sub main()
init
compile ("17/91, 78/85, 19/51, 23/38, 29/33, 77/29, 95/23, 77/19, 1/17, 11/13, 13/11, 15/14, 15/2, 55/1")
Debug.Print "First 20 results:"
output = run(2)
Debug.Print "First 30 primes:"
Debug.Print "after"; filter_primes(2, 30); "iterations."
End Sub</lang>{{out}}
<pre>First 20 results:
15 825 725 1925 2275 425 390 330 290 770 910 170 156 132 116 308 364 68 4 30
First 30 primes:
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 101 103 107 109 113
after 2019962 iterations.</pre>
=={{header|zkl}}==
<lang zkl>var fracs="17/91, 78/85, 19/51, 23/38, 29/33, 77/29, 95/23, 77/19, 1/17,"
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