Best way to find out is to declare a two dimensional VECTOR array in SED and hit Run. If you get an error, it's not possible. If you don't, it is possible.
Experimentation is the best way to learn programming if you ask me. Don't be afraid of the compiler yelling at you, it doesn't care. If you WISH something worked, try it, and worst case you'll know it doesn't if you get a compiler error. Best case, you just solved your own problem.