[std-interval] list of functions for intervals

Fernando Cacciola fernando_cacciola at datafull.com
Mon Jun 5 18:17:29 PDT 2006


Guillaume Melquiond wrote:
>
>        A' <- acos_rel(B, A)
>
> If acos_rel was not available, the second assignation could be written
> A' <- intersection(acos(B), A). But the set A' would then be wrong if
> the initial sets were A = B = [-1,1].
>
Hmm, I thought I understood the xyz_rel(X,R) functions to be precisely the 
equivalent of intersection(xyz(X),R), yet you explicetely state here that is 
not; but I can't follow: why would intersection(acos([-1,1]),[-1,1]) be 
wrong? That is, what exactly is the result of acos_rel([-1,1],[-1,1]) and 
how is that different from the explicit restriction to R?

TIA

Fernando Cacciola
SciSoft
http://fcacciola.50webs.com/




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