--- Richard Fateman wrote:
> I also suggest that we might add, in the documentation, notes that
> give some advice, like "This command exists for compatibility with
old
> programs. We suggest you use ..... for new programs. {e.g. ev vs.
> subst}" or "Some people expect this command to do ... but this is not
> its objective. {e.g. factor}"
I guess in my still-newbie mind I still find it a bit odd that subst is
a replacement for ev. I guess I really shouldn't, but if we are really
going to do away with ev I'd rather make it an inoperative command
altogether, since (to my mind at least) it is rather seductive. When I
think of the ev command, I think "defining my own local specialized
environment within which this expression will be evaluated." What that
implies I probably haven't thought through properly, and I'm not sure
anyone has (or even if they really can). But I don't immediately think
of "subst", which my mind parses as "use this to substitute something
in for something else" as a substitute for ev. So one of these
releases (not this one though) I'd like to see us decide some final
resolution to this. Clearly the strongest proponent of ev was the old
Maxima documentation, since it has little current support. Given
another development cycle or so Maximabook will need the part relevant
to ev revamped somewhat anyway, once I bring it back to life again, so
I'm no longer worried about that. But I think the whole business of
ev, subst, ratsubst, whatever the part commands are, etc. should be
written up (probably as its own chapter) and clearly explained,
defined, measured, whatever. Kill whatever isn't good, and add
robustness where needed (in docs if no other place.) I think this
concept will be an important one to hammer out with finalty early on,
since a) a lot of other behaviors will depend on it and b) it's one
even new users are likely to start using early on.
Maybe it won't be so hard to sort out, but if ev is not a good command
to use than IMHO it should die.
CY
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