I want to do some calculation like this:
[cos(theta), -sin(theta)] [Ld*p + R, -Lq*omega] [cos(theta),
sin(theta)] [Id]
*
* *
[sin(theta), cos(theta)] [Ld*omega, Lq*p + R] [-sin(theta),
cos(theta)] [Iq]
This is a part of motor equation expressed in matrix multiplication，Id, Iq,
theta are functions of t (time), p is the differential operator, so this
isn't a simple multiplication. I will do this kind of calculation a lot, so
I want to find a generic method.
在 2013年1月26日星期六UTC+9下午10时45分08秒，Stefan Krastanov写道：
>
> Before suggesting a solution I need to point out a problem with your
> suggestion. Namely, multiplication and application are two very
> different operation (there is overlap (e.g. matrix multiplication) but
> I will leave it out for the moment). SymPy does not have support for
> this type of "abuse of notation" for the moment. If you are
> interesting implementing it yourself your best shot (in my opinion)
> would be to get inspiration by the matrix expression module and the
> rewrite rules module.
>
> On the other hand if you want to use simple vanilla python for all
> this you can just use the `diff` global function but presumably you do
> not want that in order to facilitate automatic simplifications like
> "2*p - p -> p".
>
> If this is the case (and you are absolutely sure that this is
> necessary (usually it is not)) you can try to use the differential
> geometry module (in differential geometry vector fields are
> differential operators). If you know the formalism it will be very
> easy to use, however if you do not know it you will need to read
> something more than just the documentation.
>
>
> http://docs.sympy.org/dev/modules/diffgeom.html#sympy.diffgeom.BaseVectorField
>
>
> On 25 January 2013 23:49, ruoyu zhang <[email protected] <javascript:>>
> wrote:
> >>>> p = DifferentialOperator(t)
> >>>> a * p * f(t)
> > Derivative(f(t), t)*a
> >
> > p is a DifferentialOperator, when it multiply with some expression at
> right
> > side, it calculates the derivative of the expression.
> >
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