Takes a scalar field as input and produces a vector field.

Mnemonic: the gradient shows the direction in which the function increases fastest.

Think of a color gradient going from white to black from left to right.

Therefore, it has to:

- take a scalar field as input. Otherwise, how do you decide which vector is larger than the other?
- output a vector field that contains the direction in which the scalar increases fastest locally at each point. This has to give out vectors, since we are talking about directions

- Gradient, Divergence, Curl, and Laplacian | 0, 306, 7
- Calculus | 17, 7k, 159
- Mathematics | 17, 13k, 336
- Ciro Santilli's Homepage | 262, 182k, 3k

- Derivation of the Klein-Gordon | 253
- Four-gradient | 38
- Lagrangian density | 319
- Momentum operator | 115