Comment

Comment on So much

davidagain@lemmy.world ⁨2⁩ ⁨months⁩ ago

There’s notation for that - (x0 - δ, x0 + δ), so you could say
f(x0 - δ, x0 + δ) ⊂ (L - ε, L + ε)

Sort:hotnew top

affiliate@lemmy.world ⁨2⁩ ⁨months⁩ ago
that would be a lot clearer. i’ve just been burned in the past by notation in analysis.

my two most painful memories are:

in the (baby) rudin textbook, he uses f(x+) to denote the limit of _f _from the right, and f(x-) to denote the limit of f from the left.

in friedman analysis textbook, he writes the direct sum of vector spaces as M + N instead of using the standard notation M ⊕ N. to make matters worse, he uses M ⊕ N to mean M is orthogonal to N.

there’s the usual “null spaces” instead of “kernel” nonsense. ive also seen lots of analysis books use the → symbol to define functions when they really should have been using the ↦ symbol.

at this point, i wouldn’t put anything past them.
source
- davidagain@lemmy.world ⁨2⁩ ⁨months⁩ ago
  Egregious. I feel your pain.
  
  source