But when you said $$ \frac {\partial} {\partial x} $$ multiplied by a scalarTach said:It is not that I disagree with Penrose, it is that you misinterpret what he's writing.

*is not a vector*, you said it was "nonsense", you

*weren't*misinterpreting what Penrose was saying? Because that's what he says in his book.

Actually what he says is the scalar should be a function of x (or whatever variable is being varied). But as others have noted that's a mere mathematical detail because a vector multiplied by any scalar

*is still a vector*. That's something I learned in a linear algebra course.

Last edited: