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## No. 679: This comic is banned in mathematics exams

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Permanent URL: https://mezzacotta.net/dinosaur/?comic=679

Strip by: David Morgan-Mar

T-Rex: T-Rex solves a partial differential equation!
T-Rex: f(Du, u, x) = 0 where u = u(x)
T-Rex: And x is a vector of arbitrary dimension and Du is a matrix of partial derivatives.
T-Rex: First we find F such that F′(Du, u, x) ≈ f(Du, u, x)
Utahraptor: Isn't that harder than just solving f(Du, u, x) = 0 in the first place?
T-Rex: Well sure... but that's
T-Rex: NO FUN!

The author writes:

Utahraptor interrupted T-Rex's line of thought:

First we find F such that F′(Du, u, x) ≈ f(Du, u, x), and solve F(Du, u, x) = any constant value. Then simply differentiate F to find an approximate form for f.

Which is obviously more fun.