This function presents a warning to the user if major elements exist which are not discretised. (This will happen if a major element(s) is large compared to the ``maximum segment length'', resulting in a meshing requirement of more than 50 lines in either direction.) If only one or two major elements cause problems, they can be divided into smaller major elements. If most of the elements are too large for discretisation, the ``maximum segment length'' should be adjusted accordingly.