Total number of fields: 3.
Creating a 2-dimensional structured regular mesh of 5x5x5 in memory and creating a DM object.
Setting field names to DM: 
	 Field{0} = v1.
	 Field{1} = v2.
	 Field{2} = v3.
Creating a global vector defined on DM and setting random data.
Creating a global matrix defined on DM with the right block structure.