Hello Mario!

Replying to a message of Mario Semo to Erik Huelsmann:

 MS> a) The Art of Computer Programming. (Knuth). Part1 ? 
 MS> (Fundamental Algorithms). Page 336 talsk about preOrder, postOrder
 MS> presentation of formulas extracted from the binary tree presentation
 MS> of the formula. 

 MS> b) you have to parse the expression and build a parse tree and use
 MS> postorder traversal methods.
I will check out your book recommendation. I think it will shed some light
on my case...

 EH>> X*(X'*X)^(-1)*X'*y
 EH>> X X ' X * -1 ^ X * y *

 MS> to parse such expressions, i would use an LEX/YACC tool. I don't know
 MS> if such a tool is available for Pascal. (the lexx/yacc i can write
 MS> such a parser/scanner in a few lines of code).
I could probably get such a tool, but I don't know how to work them :-(, if
I would, I would probably have written a dll to stuff the parser in....

 MS> But of course you can implement the parser for yourself. if you don't
 MS> know how to write an lexical parser for an LR1 grammatic, i would
 MS> suggest a book about compiler construction. 
Figured this would be the fastest way, considering that I would have to
learn C for writing the dll...

 MS>  WARPED!, Mario

Bye, Erik!


 *** I am slowly getting there, but Sibyl is getting me there faster :-)
 *** Q's? e-mail me at ErikH{at}hcc-gron.idn.nl

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