Height is 'a function of' age in children. [=the height of children increases as their age increases]
His bad health has prevented him from being able to 'function' effectively in recent weeks.
Her chief/main/primary/principal 'function' is to provide expert legal advice.
(..) Back when they lost what made them people. Your job is to stay sane enough so when someone does come in that you can help, you're not so braindead you can't function. For the love of God, what? Should we be talking about this in front of... Her? She's dead. Write this down. (..)2001 TvShow: Scrubs Title: My First Day Season: 1 Episode 1