Hi
I am working on PDE's and I am trying to get the symbolic expression for
multivariabe finite differences
mainly I wan the expression for d/dx(d/dy f), however
d2pdxdy=as_finite_diff(p(x,y,z,t).diff(x,y),[x,x-h,y,y+h])
doesn't work, nor any possible combination. Is this just not implemented
What is the answer that you would expect to get?
Aaron Meurer
On Wed, Mar 16, 2016 at 12:12 PM, Mathias Louboutin
wrote:
> Hi
>
> I am working on PDE's and I am trying to get the symbolic expression for
> multivariabe finite differences
>
> mainly I wan the expression for d/dx(d/dy f), however
>
.5 * (p(x,y+h) - p(x,y) - p(x-h,y+h) + p(x-h,y+h) ) / h^2
Le mercredi 16 mars 2016 21:09:53 UTC, Aaron Meurer a écrit :
>
> What is the answer that you would expect to get?
>
> Aaron Meurer
>
> On Wed, Mar 16, 2016 at 12:12 PM, Mathias Louboutin
> > wrote:
> > Hi
> >
> > I am working on PDE
In this example case it would give
.25 * ( p(x,y+h,z,t) - p(x,y,z,t) + p(x-h,y,z,t) - p(x-y,y+h,z,t) ) /h^2
But more generally I would want to be able to take the result
of as_finite_diff as a new expression I can differentiate :
a = as_finite_diff ( f(.).diff(x) )
b= as_finite_diff( a.di
As far as I can tell, the function only supports finite differences of
one variable at a time. My guess is that it wouldn't be too hard to
extend it to do what you want, though.
Aaron Meurer
On Thu, Mar 17, 2016 at 7:07 AM, Mathias Louboutin
wrote:
> In this example case it would give
>
> .25 *
