Modifications to add! (#41)

With these changes it's possible to give `dofs1` and `dofs2` eg. in
sub-arrays or tuples, not only vectors. Also, `data` can be a long
vector in row-major order (`data_vec = vec(data)`).

src/sparse.jl

@@ -111,11 +111,14 @@ Matrix(A)
  0.0  0.0  0.0  0.0  0.0  8.0  9.0  10.0
 ```
 """
-function add!(A::SparseMatrixCOO, dofs1::Vector{Int}, dofs2::Vector{Int}, data)
-    n, m = size(data)
+function add!(A::SparseMatrixCOO, dofs1::AbstractVector{Int}, dofs2::AbstractVector{Int}, data)
+    n, m = length(dofs1), length(dofs2)
+    @assert length(data) == n*m
+    k = 1
     for j=1:m
         for i=1:n
-            add!(A, dofs1[i], dofs2[j], data[i,j])
+            add!(A, dofs1[i], dofs2[j], data[k])
+            k += 1
         end
     end
     return nothing

test/test_assembly.jl

@@ -78,8 +78,8 @@ end
     A = Assembly()
     B = Assembly()
     @test isempty(A)
-    add!(A.K, [1,2,3,4], [1,2,3,4], [1.0 2.0; 3.0 4.0])
-    add!(B.K, [1,2,3,4], [1,2,3,4], [1.0 2.0; 3.0 4.0])
+    add!(A.K, [1,2], [1,2], [1.0 2.0; 3.0 4.0])
+    add!(B.K, [1,2], [1,2], [1.0 2.0; 3.0 4.0])
     @test isapprox(A, B)
     @test !isempty(A)
     empty!(A)