In plane analytic geometry, the gradient is an increase in y corresponding to a unit increase in x. The gradient of a curve may be found at any point along it by use of differential calculus. Gradient is a vector quantity. In vector notation, the gradient of a scalar field W is the vector field

 

    grad W = i ∂W/∂x + j ∂W/∂y + k ∂W/∂z

 

In other words, the gradient is a vector of partial derivatives of a function that operates on vectors.