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JuliaFEM.jl/src/problems.jl
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Julia

# This file is a part of JuliaFEM.
# License is MIT: see https://github.com/JuliaFEM/JuliaFEM.jl/blob/master/LICENSE.md
abstract AbstractProblem
type FieldProblem{T<:AbstractProblem}
name :: ASCIIString
dim :: Int
elements :: Vector{Element}
end
type BoundaryProblem{T<:AbstractProblem}
name :: ASCIIString
parent_field_name :: ASCIIString
parent_field_dim :: Int
dim :: Int
elements :: Vector{Element}
end
typealias Problem FieldProblem
typealias AllProblems Union{FieldProblem, BoundaryProblem}
function get_elements(problem::AllProblems)
return problem.elements
end
""" Return the dimension of the unknown field of this problem. """
function get_unknown_field_dimension(problem::Problem)
return problem.dim
end
""" Return the name of the unknown field of this problem. """
function get_unknown_field_name{P<:AbstractProblem}(problem::Problem{P})
return get_unknown_field_name(P)
end
function Base.push!(problem::AllProblems, element::Element)
push!(problem.elements, element)
end
# TODO: better place for utility functions?
""" Calculate "nodal" vector from set of elements.
For example element 1 with dofs [1, 2, 3, 4] has [1, 1, 1, 1] and
element 2 with dofs [3, 4, 5, 6] has [2, 2, 2, 2] the result will
be sparse matrix with values [1, 1, 3, 3, 2, 2].
Parameters
----------
field_name
name of field, e.g. "geometry"
field_dim
degrees of freedom / node
elements
elements used to calculate vector
time
"""
function calculate_nodal_vector{T}(field_name::ASCIIString, field_dim::Int, elements::Vector{Element{T}}, time::Real)
A = SparseMatrixCOO()
b = SparseMatrixCOO()
for element in elements
haskey(element, field_name) || continue
gdofs = get_gdofs(element, 1)
# info("gdofs = $gdofs")
for ip in get_integration_points(element, Val{2})
J = get_jacobian(element, ip, time)
w = ip.weight*norm(J)
f = element(field_name, ip, time)
N = element(ip, time)
add!(A, gdofs, gdofs, w*kron(N', N))
for dim=1:field_dim
add!(b, gdofs, w*f[dim]*N, dim)
end
end
end
A = sparse(A)
b = sparse(b)
nz = sort(unique(rowvals(A)))
x = zeros(size(b)...)
x[nz, :] = A[nz,nz] \ b[nz, :]
return vec(transpose(x))
end