Data commit

Task/Farey-sequence/FreeBASIC/farey-sequence.basic

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