On Saturday 23 January 2010 14:55:08 Garth N. Wells wrote: > Johan Hake wrote: > > On Saturday 23 January 2010 08:42:14 Garth N. Wells wrote: > >> Is it correct that behind the scenes that > >> > >> U0 = Function(V) > >> U = Function(V) > >> U0.vector()[:] = U.vector()[:] > >> > >> involves a GenericVector::get(..) call and a GenericVector::set(..) > >> call? If so, it isn't ideal since it introduces unnecessary new/delete > >> operations and unnecessary copying of data. > > > > None of GenericVector::get(..) or GenericVector::set(..) are invoked, see > > __getslice__ and __setslice__ in la_post.i. > > > > U0.vector()[:] > > > > involves > > > > GenericVector::operator =(..) > > > > and > > > > U.vector()[:] > > > > involves > > > > GenericVector::copy() > > > > However the latter is unnecessary as you instead can do: > > > > U0.vector()[:] = U.vector() > > > > invoking the assignment operator of U0's vector with U's vector. > > What happens if I do > > x = U.vector()[:]
It just triggers the copy method of GenericVector, which is the same behavior as for other itterable Python types. > ? Is x a numpy array? No you need to call array() to accomplish that. Johan > Garth > > > Johan > _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : [email protected] Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
