Math : Partial / Gradeint/ Directional / Gradient op/ Laplace op

 Partial derivative

https://www.youtube.com/watch?v=kdMep5GUOBw

https://www.youtube.com/watch?v=dfvnCHqzK54



finding partial derivative = finding a slope



partial derivative with respect to x is like below


and the partial derivative with respect to y is like below


Confirm partial derivative by graphs

the partial derivative with respect to x 


the partial derivative with respect to y


The formal definition of partial derivatives


The symmetry of second partial derivatives


Gradient 


∇ = is being a vector full of partial derivative operators



Gradient and graphs



Gradient ∇f is shown like this on the graph.

* which means the direction of the steepest ascent.


Directional derivative


Divergence formula 

only x component gradient value.




only y component gradient value




Laplacian intuition

f(x,y)

Δf(x,y) 

div(grad f) = ∇ㆍ∇f

what does the divergence represent? 

gradient / direction to increase the slope

case of divergence positive and negetive


and in and out is 0 divergence


* Δf(x,y) is like how much of a minimum point is this X, Y.


Laplacian computation example

f(x,y) = 3 + cos(x/2) sin(y/2)


Δf = ∇·∇f


divergence of the gradient is laplacian


Explicit Laplacian formula

f (x₁, x₂ , --- , xn)      Δf = ∇·∇f


formula for Laplacian



Curl 1 | Partial derivatives, gradient, divergence, curl | Multivariable Calculus






∇ × V = div(V)


∇ × V = curl(V) which means the measure of how much is that field rotating.


Curl example




















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