Talk:Anonymous recursion: Difference between revisions
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::Since the J solution acts like an identity when called with negative arguments the check for negative numbers can be performed after the fibonacci function is called, signalling a domain error if the result is negative: <lang J>fibN =: 3 : '[:^:(0&>) (-&2 +&$: -&1)^:(1&<) M. y'"0</lang> Alternatively using a control structure: <lang J>(3 : 'if. y<0 do. <''negative argument'' else. <(-&2 +&$: -&1)^:(1&<) M. y end.'"0)</lang> --[[User:Zeotrope|Zeotrope]] 19:48, 8 January 2011 (UTC) |
::Since the J solution acts like an identity when called with negative arguments the check for negative numbers can be performed after the fibonacci function is called, signalling a domain error if the result is negative: <lang J>fibN =: 3 : '[:^:(0&>) (-&2 +&$: -&1)^:(1&<) M. y'"0</lang> Alternatively using a control structure: <lang J>(3 : 'if. y<0 do. <''negative argument'' else. <(-&2 +&$: -&1)^:(1&<) M. y end.'"0)</lang> --[[User:Zeotrope|Zeotrope]] 19:48, 8 January 2011 (UTC) |
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:::The J solution does indeed check if the number is negative before using recursion, and will not use recursion with a negative argument. (Any number which is negative is not greater than 1, and the J solution checks to see if the number is greater than 1 before using recursion.) That said, the task does not specify the result to be returned for negative values. --[[User:Rdm|Rdm]] 03:25, 9 January 2011 (UTC) |
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== Recursion implies a function == |
== Recursion implies a function == |
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