55 lines
1.2 KiB
Plaintext
55 lines
1.2 KiB
Plaintext
' version 05-04-2017
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' compile with: fbc -s console
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' TRUE/FALSE are built-in constants since FreeBASIC 1.04
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' But we have to define them for older versions.
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#Ifndef TRUE
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#Define FALSE 0
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#Define TRUE Not FALSE
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#EndIf
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Function farey(n As ULong, descending As Long) As ULong
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Dim As Long a, b = 1, c = 1, d = n, k
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Dim As Long aa, bb, cc, dd, count
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If descending = TRUE Then
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a = 1 : c = n -1
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End If
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count += 1
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If n < 12 Then Print Str(a); "/"; Str(b); " ";
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While ((c <= n) And Not descending) Or ((a > 0) And descending)
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aa = a : bb = b : cc = c : dd = d
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k = (n + b) \ d
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a = cc : b = dd : c = k * cc - aa : d = k * dd - bb
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count += 1
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If n < 12 Then Print Str(a); "/"; Str(b); " ";
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Wend
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If n < 12 Then Print
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Return count
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End Function
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' ------=< MAIN >=------
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For i As Long = 1 To 11
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Print "F"; Str(i); " = ";
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farey(i, FALSE)
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Next
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Print
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For i As Long= 100 To 1000 Step 100
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Print "F";Str(i);
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Print iif(i <> 1000, " ", ""); " = ";
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Print Using "######"; farey(i, FALSE)
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Next
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' empty keyboard buffer
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While Inkey <> "" : Wend
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Print : Print "hit any key to end program"
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Sleep
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End
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