>
> Alasdair wrote:
> >
> > Actually, there's one minor problem: the mixed partial derivatives are
> > treated as different objects, so I have to do
> >
> > kxy := eval(D(f(x,z),[x,z]),z=y(x))
> > > kyx := eval(D(f(x,z),[z,x]),z=y(x))
> > >
> > > subst(f2,[kxy=F[xy],kyx=F[xy])
> > >
> >
> > which is clearly going to become prohibitive for larger numbers of
> > variables. How can I convince Fricas that D(f(x,z),[x,z]) and
> > D(f(x,z),[z,x]) are in fact the same?
>
> I am affraid that ATM substitution is the only way. FriCAS
> should automatically do such simplification, I will try to
> implement this.
I have commited such change. With current trunk:
(1) -> f := operator 'f
(1) f
Type: BasicOperator
(2) -> y := operator 'y
(2) y
Type: BasicOperator
(3) -> kxy := eval(D(f(x,z),[x,z]),z=y(x))
(3) f (x,y(x))
,1,2
Type: Expression(Integer)
(4) -> kyx := eval(D(f(x,z),[z,x]),z=y(x))
(4) f (x,y(x))
,1,2
Type: Expression(Integer)
(5) -> kxy - kyx
(5) 0
Type: Expression(Integer)
--
Waldek Hebisch
[email protected]
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