Carl Witty wrote:
> On Tue, Jun 9, 2009 at 6:08 PM, Golam Mortuza
> Hossain<gmhoss...@gmail.com> wrote:
>> Hi,
>>
>> On Tue, Jun 9, 2009 at 9:45 PM, Jason Grout<jason-s...@creativetrax.com>
>> wrote:
>>
>>>> (4) Should we switch to old maxima format for "diff"?
>>> Can you clarify with an example what you mean? In other words, can you
>>> give an example of the "new" way and the "old" way?
>> In new symbolics, "df(x)/dx" is
>>
>> (a) represented as: D[0] f(x)
>> (b) typeset as: D[0] f(x)
>>
>>
>> In old symbolics, the same was
>>
>> (a) represented as: diff( f(x), x)
>> (b) typeset as: \frac{d f(x)}{d x}
>
> Is it even possible to use the old typesetting format with the new
> symbolic representation? For example, "df(sin(x)*cos(x))/dx" is
> represented as -(sin(x)^2 - cos(x)^2)*D[0](f)(sin(x)*cos(x)); it seems
> likely to be difficult to invert that to produce
>
> {{{\it \partial}}\over{{\it \partial}\,x}}\,f\left(\cos x\,\sin x \right)
>
> (which is what the old symbolics produced). And what should
> "D[0](f)(sin(x)*cos(x))" be typeset as?
How about:
-(sin(x)^2-cos(x)^2)*\frac{df}{dx}(sin(x)*cos(x))
That's how I'd write it in class if I was illustrating the chain rule.
I agree with Robert---functions have ordered, named parameters (thanks
to your patch that deprecated not specifying the order of variables!),
so we should be able to convert back and forth between D[i](f) and
\frac{df}{d<parameter>} or \frac{\partial f}{\partial<parameter>}
unambiguously.
Jason
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