Relative clauses

Sorry, the formatting didn't work. I'll write the question out again. In the sentence 'A functional is a machine which turns a function into a number.' is 'A functional is a machine' a relative clause and need to be corrected to 'A functional is a machine, which turns a function into a number.'?

No, "A functional is a machine" is an independent clause. "Which turns a function into a number" is a relative clause.

A functional is actually a function that maps a vector to a scalar. If the vector belongs to a space of functions and the scalar is the real numbers, then your statement makes some sense. But "which turns a function into a number" is (a somewhat metaphorical) definiti

Thank you for your excellent answer. I am aware the statement is not mathematically correct. I saw the statement in a book, in which it is used somewhat metaphorically as you said, and was unsure about the grammar.

I hope that my explanation of the grammar made up for my pedantry on the mathematics. Sorry about the latter.