Author: Peter Fendrich
Date: 04:40:53 09/15/03
Go up one level in this thread
On September 15, 2003 at 07:05:38, Uri Blass wrote: >On September 15, 2003 at 05:53:40, Peter Fendrich wrote: > >>On September 15, 2003 at 03:39:33, Uri Blass wrote: >> >>>On September 15, 2003 at 02:56:24, Reinhard Scharnagl wrote: >>> >>>>Hi Uri, >>>> >>>>>Can programmers write a program that take a code with recursive functions and >>>>>translate it to a code without recursive functions that does the same thing? >>>>> >>>>>Do not answer me that the compiler does it by translating it to assembler >>>>>because the translation should be done to a program in the same computer >>>>>language so a C source should be translated to another C source. >>>> >>>>it could be done by locally implementing a kind of a stack. You have >>>>therefore to think about maximum call limits. Sometimes a simple loop >>>>already will do the aimed task. >>>> >>>>But what is the reason for such a non recursiv approach? What is >>>>wrong with using recursion? >>>> >>>>Regards, Reinhard. >>> >>>I read that recursion is bad for parallel program and there is information >>>that I practically remember twice so maybe it is not good also for non parallel >>>program. >>> >>>If I want to check if the king was in check 2 plies earlier then I need to look >>>at a special array for that purpose and I understand that with non recursive >>>approach I can get the information without remembering it twice. >> >>I can't really see the differrence in this respect. If you don't use recursion >>you will instead use an iteration (while or for). IMO a very inelegant >>solution... >>Anyway, You have to put basically all data used locally by the former recursive >>function in an array indexed by plynumber. In order to check if the king was in >>check 2 plies up you still need to look in the array with the index ply-2. >>Am I missing something? "Remember it twice" doesn't make sence to me... > >The point is that the computer remember twice if the king was in check 2 plies >ago(one time in an array and one time when I go back in the search because I >have a global varaible kingincheck that tells it if the king is in check. Ok, I don't do it like that. If the king is in check is not global in my program but strictly asociated with each node. Everything that has to be accessed from another node (= another ply) is put in an array like the one I described above. "InCheck" is one of them. Once computed it is there to be used. BTW. Such global variables as yours should not be used in parallell programs at all because they are messed up by the threads, so I don't understand what Vincent might mean by this. >I understood from a post of vincent that non recursive >search avoid the problem and it is not harder to change a program with non >recursive search. It's maybe not harder to change the code but probably harder for the compiler to optimize it. >The claim was that it is important for parallel search but I think that >considering what happened in previous nodes for future decisions can be >important not only for parallel search. >Uri
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.