copy!(SparseMatrixCSC, MKLSparseMatrix)

src/mklsparsematrix.jl

@@ -201,9 +201,27 @@ Base.convert(::Type{SparseMatrixCSC}, A::MKLSparseMatrix{SparseMatrixCSC{Tv, Ti}
 function Base.convert(::Type{S}, A::MKLSparseMatrix{S}) where {S <: SparseMatrixCSR}
     _A = extract_data(A)
     # not converting the col indices depending on index_base
-    @show length(_A.nzval)
     return S(_A.size..., copy(_A.major_starts), copy(_A.minor_val), copy(_A.nzval))
 end
 
 Base.convert(::Type{SparseMatrixCSR}, A::MKLSparseMatrix{SparseMatrixCSR{Tv, Ti}}) where {Tv, Ti} =
     convert(SparseMatrixCSR{Tv, Ti}, A)
+
+# copy the non-zero values from the MKL Sparse matrix A into the sparse matrix B
+# A and B should have the same non-zero pattern
+function Base.copy!(B::S, A::MKLSparseMatrix{S};
+                    check_nzpattern::Bool = true) where {S <: SparseMatrixCSC}
+    _A = extract_data(A)
+    Ti = eltype(B.rowval)
+    length(_A.nzval) == nnz(B) || error(lazy"Number of nonzeros in the source ($(length(_A.nzval))) does not match the destination matrix ($(nnz(B)))")
+    size(B) == _A.size || throw(DimensionMismatch(lazy"Size of the source $(_A.size) does not match the destination $(size(B))"))
+    if check_nzpattern
+        B.colptr == _A.major_starts || error("Source and destination colptr do not match")
+        rowval_match = _A.index_base == SPARSE_INDEX_BASE_ZERO ?
+            all((a, b) -> a + one(Ti) == b, zip(_A.minor_val, B.rowval)) : # convert to 1-based
+            _A.minor_val == B.rowval
+        rowval_match || error("Source and destination rowval do not match")
+    end
+    (pointer(B.nzval) != pointer(_A.nzval)) && copy!(B.nzval, _A.nzval)
+    return B
+end