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fibonacci_tail_recursive.scala

 1 /* Copyright (c) 2008 the authors listed at the following URL, and/or
 2 the authors of referenced articles or incorporated external code:
 3 http://en.literateprograms.org/Fibonacci_numbers_(Scala)?action=history&offset=20080924141203
 4 
 5 Permission is hereby granted, free of charge, to any person obtaining
 6 a copy of this software and associated documentation files (the
 7 "Software"), to deal in the Software without restriction, including
 8 without limitation the rights to use, copy, modify, merge, publish,
 9 distribute, sublicense, and/or sell copies of the Software, and to
10 permit persons to whom the Software is furnished to do so, subject to
11 the following conditions:
12 
13 The above copyright notice and this permission notice shall be
14 included in all copies or substantial portions of the Software.
15 
16 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
19 IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
20 CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
21 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
22 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23 
24 Retrieved from: http://en.literateprograms.org/Fibonacci_numbers_(Scala)?oldid=14722
25 */
26 
27 
28   def fib( n:Int) = fib_tr( n, 1, 0) 
29 
30   def fib_tr( n: Int, b: Int, a: Int): Int = n match {
31 
32     case 0 => a 
33     case _ => fib_tr( n -1, a + b, b)
34   }
35


fibonacci_recursive.scala

 1 /* Copyright (c) 2008 the authors listed at the following URL, and/or
 2 the authors of referenced articles or incorporated external code:
 3 http://en.literateprograms.org/Fibonacci_numbers_(Scala)?action=history&offset=20080924141203
 4 
 5 Permission is hereby granted, free of charge, to any person obtaining
 6 a copy of this software and associated documentation files (the
 7 "Software"), to deal in the Software without restriction, including
 8 without limitation the rights to use, copy, modify, merge, publish,
 9 distribute, sublicense, and/or sell copies of the Software, and to
10 permit persons to whom the Software is furnished to do so, subject to
11 the following conditions:
12 
13 The above copyright notice and this permission notice shall be
14 included in all copies or substantial portions of the Software.
15 
16 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
19 IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
20 CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
21 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
22 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23 
24 Retrieved from: http://en.literateprograms.org/Fibonacci_numbers_(Scala)?oldid=14722
25 */
26 
27 
28   def fib( n: Int): Int = n match {
29 
30     case 0 => 0
31     case 1 => 1
32     case _ => fib( n -1) + fib( n-2)
33   }
34


fibonacci_iterative.scala

 1 /* Copyright (c) 2008 the authors listed at the following URL, and/or
 2 the authors of referenced articles or incorporated external code:
 3 http://en.literateprograms.org/Fibonacci_numbers_(Scala)?action=history&offset=20080924141203
 4 
 5 Permission is hereby granted, free of charge, to any person obtaining
 6 a copy of this software and associated documentation files (the
 7 "Software"), to deal in the Software without restriction, including
 8 without limitation the rights to use, copy, modify, merge, publish,
 9 distribute, sublicense, and/or sell copies of the Software, and to
10 permit persons to whom the Software is furnished to do so, subject to
11 the following conditions:
12 
13 The above copyright notice and this permission notice shall be
14 included in all copies or substantial portions of the Software.
15 
16 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
19 IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
20 CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
21 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
22 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23 
24 Retrieved from: http://en.literateprograms.org/Fibonacci_numbers_(Scala)?oldid=14722
25 */
26 
27 
28   def fib( n: Int) = {
29     // initial values

30     var a = 0    // inferred type: Int

31     var b = 1    // inferred type: Int

32     
33     // function next

34     // inferred result type: Pair[Int, Int]

35     
36     def next( a: Int, b: Int) = Pair( b, a + b) ;    
37   
38     var i = 0
39     while( i < n) {
40       
41       // get result pair members by pattern matching

42       val Pair( c, d) = next( a, b) ;
43       
44       // assign result

45       a = c
46       b = d
47       
48       //iterate

49       i = i +1
50     }
51     // return 'a'

52     a
53   }
54


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