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Re: What is the innermost loop: bug or feature?




Dear Jack,

I am sorry to be so long in getting back to you about
the mysteries of inner loops.  to you question:
 
>Bug or feature? 

"embarrassment" would be a better term.  a bit of history.
sage was originally developed from an older library that
was used to loop transformations on fortran programs.
(one of our partners  IRISA in France still does lots of this
and they have contributed a great deal to sage.)  anyway,
they did the origninal versions of these loop operators
and they only intended then to work on "perfect" loop nests,
i.e. loops that contain only one statement which is another
loop (the innermost was allowed to contain an arbitrary block.)
these operators were not well defined in any other context,
so that means we can extend the meaning as we wish.
So we can do so if you have ideas along these lines.  However
we should be consistant with the ways our French friends do things.
I will check with them on the semantics that they want to preserve
and if you have suggestions of what should be done in the other
cases we would welcome them.

sincerely,
dennis gannon