On Wednesday 22 September 2004 20:12, Jack Dyson wrote:
> Hi all,
>
> I have been recently trying to simplify some vector calculus and
> although vect.mac is very good generally, it is giving me incorrect
> answers on a type of calculation. I wonder if this is the lack of
> experience showing on my part or a genuine error? - any help with this
> would be appreciated...
>
> PROBLEM: (assume vect package is loaded)
>
> declare([u,v],nonscalar);
> declare(phi,scalar);
> ev(vectorsimp(grad(phi*v)),expandall:true);
In your notations, grad(phi*v) has no sence. Do you mean div(phi*v)?
Yet, I did not find function grad in the package "vect'. There is one in
another package "vector". This package is known to be broken.
Please, be more specific and give us the output of maxima session.
There is another point for thoughts. What about using "itensor" for vector
calculus? With help of "itensor/ctensr" you will be able to get the coordinat
reperesentations for any complicated vector or tensor expression.
best regards,
Valery