Gradient-related

Gradient-related is a term used in multivariable calculus to describe a direction. A direction sequence formula_1 is "gradient-related" to formula_2 if for any subsequence formula_3 that converges to a nonstationary point, the corresponding subsequence formula_4 is bounded and satisfies"
formula_5
Gradient-related directions are usually encountered in the gradient-based iterative optimization of a function formula_6. At each iteration formula_7 the current vector is formula_8 and we move in the direction formula_9, 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.