Hi,
On Thu, Jul 23, 2009 at 3:06 PM, Burcin Erocal<bur...@erocal.org> wrote:
> I am not opposed to having the unevaluated diff as an alternative
> operator.
Thanks Burcin. Surely, it helps to have both derivatives available to
Sage users. As Tim said, similar options are available to Maple users.
It is easy to put a flag that will instruct which derivative to use.
For example, in my prototype I could add another condition
// No derivative defined and user wants diff format? Then dont apply chain rule
if (opt.derivative_f == NULL && use_diff_format) {
.....
...
}
The next question is then whether we evaluate symbolic derivative
using "D" by default or we store them un-evaluated using "diff"
and evaluate them in terms of "D" only on-demand?
Mock-up usage could look like
------
sage: diff( f(x), x)
diff( f(x), x, 1)
sage: diff( f(x), x, D_format=True)
D[0](f)(x)
------
Given pynac "D" construct doesn't store enough information
for guaranteed conversion to "diff" format, personally I don't
see any way out other than storing symbolic derivative
un-evaluated by default.
Cheers,
Golam,
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