Make the documentation clear about what the assign function does.

diff --git a/include/deal.II/lac/petsc_block_vector.h b/include/deal.II/lac/petsc_block_vector.h
index ab8e92d32ec058ad83e201643f5a5ddc3f4ba875..71d95890531a3132021cea74c7713f36c1d21db2 100644 (file)
--- a/include/deal.II/lac/petsc_block_vector.h
+++ b/include/deal.II/lac/petsc_block_vector.h
@@ -155,8 +155,12 @@ namespace PETScWrappers
       operator=(const BlockVector &V);
 
       /**
-       * This method assigns the PETSc Vec to the instance of the class.
+       * This method assigns the given PETSc Vec to the instance of the class.
        *
+       * Note that the vector is not copied: instead, the instance of this class
+       * is initialized to use the given vector. This is useful if you want to
+       * interpret a PETSc vector as a deal.II vector, and you already have a
+       * BlockVector that you want to use for this purpose.
        */
       void
       assign_petsc_vector(Vec v);