Hey. Yeah deep recursion is something I don't really want to deal with. :)
I've only used recursion once and that was to walk a data structure. For
this kind of problem, which is a convergence problem, I would use a loop.
I'm assuming that there is a variance value that is computed and compared to
a tolerance value. When the variance is within tolerance, u have "the answer".
Here's what I would do:
($variance, $answer) = &solver($variance, $answer) while $variance > $tolerance;
sub solver {
my ($initvari, $initanswr) = @_;
do { something; };
return ($curvari, $curanswr);
}
This gives u de facto recursion with the ease and sanity of iteration. HTH.
At 02:02 PM 5/21/2009 -0700, gai...@visioninfosoft.com wrote:
>given:
>
>a. that its generally considered to be 'bad form' to use global variables
>inside of sub-routines.
>
>b. that I need to write a recursive sub-routine to solve a mathematical
>problem.
>
>
>
>the sub-routine will recursively call itself until the 'answer' is derived.
>when the innermost call finishes executing, the program will drop through to
>the previous call, and so forth. until it drops out of the original first
>call to the function.
>
>
>
>at present, I am 'cheating' here by using a global variable to control this
>recursive behavior. when the innermost loop finds the 'answer', the global
>variable is set to $weve_found_answer=1;
>
>
>
>the sub-routines then look to the value of $main::weve_found_answer to
>determine if it should stop recursively calling itself because the answer
>has already been found - or continue to recursively call itself again.
>
>
>
>for now it 'works' but its not following the 'don't use globals unless there
>is no better way' principle.
>
>
>
>so I ask. 'is there a better way of allowing each sub routines
>instantiation, at any nested level of the recursive call, be able to know
>when the answer has been found?'
>
>
>
>if anyone has any insights or experience with this, I would be very
>interested to learn from your experience
>
>
>
>thanks, greg
>
--
REMEMBER THE WORLD TRADE CENTER ---=< WTC 911 >=--
"...ne cede malis"
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