beat (one's) head against a stone wall

To attempt, continuously and fruitlessly, to accomplish some task or achieve some goal that is or seems ultimately hopeless. I feel like I've been beating my head against a stone wall trying to understand this math equation. Some people are never going to agree with you on this, so it's no use beating your head against a stone wall to try and convince everyone.

Common Names:

Name	Pronounced	Usage
Phoibos	-	Greek Mythology, Ancient Greek
Eckhard	EK-hahrt	German
Alessio	-	Italian
Vilhelmas	-	Lithuanian
Gunnhildr	-	Ancient Scandinavian
Saam	-	Persian, Persian Mythology