Author: Vincent Diepeveen
Date: 11:06:03 04/11/04
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On April 10, 2004 at 10:29:51, Dan Andersson wrote: > There are reasons for using recursion. One of them is that the generated code >tends to be smaller. And that could trumph any gains made from reducing the I disagree with the first point with regards to the data used by the processor on the stack. In my function ABISMP() which is a non recursive search using principal variation search, i never call the function ABISMP() again. I just call it 1 time. That reduces data overhead considerable. It's faster too. That it is a bit more work to get it to work than recursive search i agree with. Complex code can be very tiny though. >data. > Another one is decreasing complexity. And the ability to use induction to prove >an algorithm. Search algorithms are so complex that it is very hard to proof anything theoretically. I'm using extensions (singular also) which are of course in fact related to the complex evaluation function and nullmove with a quiescencesearch which also is unlimited in fact for checks (stack limits it to 32 ply). In short try to proof something about that. In general your proof has nothing to do with whether it is recursive or non-recursive. > I often use tail recursion as a goto with values. It usually doesn't incur any >overhead. And increases branch prediction for some types of code like parsers, Calling functions is very expensive. I do not know how low level you program but a function call a few years ago for commercial chessprograms was too expensive. Ask whether one of the commercial programs at the time used recursion. The answer is NO. >regexp and interpreters. It's all high level stuff used to learn students how things work. Not how reality works. Recursion is a good tool to teach students how to do bugfree programming. Saying it is faster than other methods is however not true. The call + ret in assembly is very expensive. >MvH Dan Andersson
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