Gradient-related is a term used in multivariable calculus to describe a direction. A direction sequence is gradient-related to if for any subsequence that converges to a nonstationary point, the corresponding subsequence is bounded and satisfies Gradient-related directions are usually encountered in the gradient-based iterative optimization of a function . At each iteration the current vector is and we move in the direction , thus generating a sequence of directions. It is easy to guarantee that the directions generated are gradient-related: for example, they can be set equal to the gradient at each point. Vector calculus