I have to mention an Icelandic mathematician's name in this report I am writing. I am following the usual practice of referring to mathematicians by just their last names.
As far as I know, Icelandic people don't have family names, their "last names" are just their fathers (or mothers??) name plus son/daughter.
Also, I understand that Icelandic people call each other by their first names even in formal contexts?
His name is
How should he be called? "Hafsteinsson" or "Hjálmtýr" or should I use the full name?