Calculus Volume 3 · free preview

Directional Derivatives and the Gradient

The directional derivative measures the rate of change in any direction, the dot product of the gradient with the direction unit vector, and the gradient points uphill with magnitude the steepest slope, perpendicular to the level curves.

1. Directional derivatives

Directional derivatives

2. The gradient

The gradient

3. Properties and applications

Properties and applications

4. The gradient in three variables

The gradient in three variables

5. Directional derivative definition

The directional derivative D_u f at (a, b) measures which rate?

6. Gradient components

The gradient of f(x, y) is which vector?

7. Steepest direction

The direction of greatest rate of increase of f at a point is which?

8. Level curve perpendicularity

The gradient at a point is perpendicular to what?

9. Unit direction requirement

The directional derivative formula D_u f = gradient dot u requires u to be what?

10. Gradient symbol name

The gradient operator's symbol is an inverted delta. As a single word, what is it called? Answer in lowercase.

11. Steepest descent direction

Minimizing steps opposite the gradient. As a sign, which? Answer with the single character.

12. Directional as dot product

D_u f equals the gradient dot which vector? Answer with the single letter u.

13. Zero directional rate

The directional derivative is zero in which direction, when the gradient is nonzero?

14. Gradient descent use

Gradient descent, stepping opposite the gradient, is a foundational algorithm of which field? Answer with two words.

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