this post was submitted on 06 Oct 2023
72 points (100.0% liked)

196

17880 readers
412 users here now

Be sure to follow the rule before you head out.


Rule: You must post before you leave.



Other rules

Behavior rules:

Posting rules:

NSFW: NSFW content is permitted but it must be tagged and have content warnings. Anything that doesn't adhere to this will be removed. Content warnings should be added like: [penis], [explicit description of sex]. Non-sexualized breasts of any gender are not considered inappropriate and therefore do not need to be blurred/tagged.

If you have any questions, feel free to contact us on our matrix channel or email.

Other 196's:

founded 2 years ago
MODERATORS
 
you are viewing a single comment's thread
view the rest of the comments
[–] bh11235 15 points 2 years ago* (last edited 2 years ago) (1 children)
  1. f is a real function from the xy plane to the reals
  2. draw a horizontal-ish band (that is, two lines) creating your favorite wobbly band shape
  3. the integral of f along a single vertical line within the band is itself a function of the line's x coordinate. Call the function g(x)
  4. What is dg/dx in terms of df/dx? lf the band were perfectly horizontal, it would just be the integral along the vertical line of df/dx within the band. But it's not, so you add a term to account for the band lines moving
  5. all this assuming f and the band are pretty enough (this is 80% of the theorem statement)
[–] lgstarn@kbin.social 2 points 2 years ago

For number 4 (or maybe a new number), if a(x) and b(x) are constant, the derivatives d/dx a(x) and d/dx b(x) are zero, so all that is left is that d/dx becomes a partial derivative and can move inside the integral.