eg. Find the directional derivative of the function phi=xyz^2 at the point (1,2,3).(adsbygoogle = window.adsbygoogle || []).push({});

Actually what is the math used for?

Let's say

phi is the temperature of air(scalar field).

∇phi will be the rate if change of temperature at (1,2,3), why the direction come out.

directional derivative of it is the velocity of air(vector field)?

If so , can I say directional derivative of it is the direction of the air?

actually this is the conclusion I made from my own study.

please give me a simple example.

Thank you

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# What is the meaning of the directional derivative of a function mean?

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