Reordering of nodal Dirichlet conditions fails

[termi-official]

MWE on master

using Ferrite
grid = generate_grid(Line, (1,));

ip = Lagrange{RefLine,1}()

dh = DofHandler(grid)
add!(dh, :u, ip)
close!(dh);

ch = ConstraintHandler(dh);
∂Ω = [1] # Triggers error in renumbering
# ∂Ω = getfacetset(grid, "left") # Works
dbc = Dirichlet(:u, ∂Ω, (x, t) -> 0)
add!(ch, dbc);
close!(ch)

perm = [2,1]
Ferrite.renumber!(dh,ch,perm)

(Edit by @KnutAM moving ip above dh)

[KnutAM]

Seems like that in

Ferrite.jl/src/Dofs/ConstraintHandler.jl

Lines 41 to 48 in 12d7259

	struct Dirichlet # <: Constraint
	f::Function # f(x) or f(x,t) -> value(s)
	facets::OrderedSet{T} where {T <: Union{Int, FacetIndex, FaceIndex, EdgeIndex, VertexIndex}}
	field_name::Symbol
	components::Vector{Int} # components of the field
	local_facet_dofs::Vector{Int}
	local_facet_dofs_offset::Vector{Int}
	end

local_facet_dofs = nodeidxs and local_facet_dofs_offset = globaldofs in

Ferrite.jl/src/Dofs/ConstraintHandler.jl

Lines 481 to 486 in 12d7259

	# for nodes
	function _update!(
	inhomogeneities::Vector{T}, f::Function, ::AbstractVecOrSet{Int}, field::Symbol, nodeidxs::Vector{Int}, globaldofs::Vector{Int},
	components::Vector{Int}, dh::AbstractDofHandler, facetvalues::BCValues,
	dofmapping::Dict{Int, Int}, dofcoefficients::Vector{Union{Nothing, DofCoefficients{T}}}, time::Real
	) where {T}

Without looking closer I guess the solution would be to update local_facet_dofs_offset in Dirichlet conditions applied to nodes. However, this seems like a bit unfortunate dual use of the Dirichlet condition...

As we also discussed potential generalisations @fredrikekre, perhaps one could keep having Dirichlet as the interface, but have specialized structs add!ed to the ConstraintHandler depending on the case (here e.g. DirichletFacet and DirichletNodal). For non-identity mappings, we could then "easily" dispatch and add different structs.