PackRat wrote: > Actually, I very deliberately had both a negative and > positive example to see how to handle both cases. The > original code had the negative. The reason behind this > portion of my question was that I was wondering whether > the negative axis-specifier meant (as in other APL commands) > working from the last dimension backward and how this would > look in J. My guess was that the _0.5th dimension might > have been a new last or next-to-last dimension, but you > didn't seem to address that question. Is that the case, > or what? And, if so, how would it look in J?
I doubt the J programming forum is the right place to be asking about the precise distinction between the APL fragments ,[-0.5] and ,[0.5]. So, I've taken the liberty of responding using the general forum. Personally, I'm not even sure I know the answer -- I've not used APL since the last millennium. If we are being precise, ,[-0.5] is probably like ,:"_1 and ,[0.5] is probably like ,:"1. This assumes that I've remembered my APL correctly, and assumes quadIO is zero. Note also that other, simpler expressions might also be equivalent, depending on the problem domain. A completely mechanical translation of APL to J would likely involve a number of rather complicated expressions which are designed to implement APL literally in J. For example, to emulate quadIO, you'd need a more complicated expression than ,:"1, and most of the time you would be far better off picking a J expression which was chosen with knowledge of what quadIO value was intended for the APL code. Finally, if you don't know what the APL code does, you might be better off writing the J code from first principles (instead of trying to translate something you don't understand). -- Raul ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
