Gradient in different cooridinates

[athrun200]

Homework Statement

Homework Equations

The Attempt at a Solution

I saw from a book this is a quick way to get gradient in different cooridinates.

However what f, g and h are? And how do I know that in rectangular coor. f=g=h=1 and etc?

 

[hunt_mat]

I am always a bit suspicious about these formulae. My advice id to go from first principles, learn how to do it and then when you need then again, look it up in a book.