Have a sneer percolating in your system but not enough time/energy to make a whole post about it? Go forth and be mid - welcome to the Stubsack, your first port of call for learning fresh Awful you’ll near-instantly regret.
Any awful.systems sub may be subsneered in this subthread, techtakes or no.
If your sneer seems higher quality than you thought, feel free to cut’n’paste it into its own post — there’s no quota for posting and the bar really isn’t that high.
The post Xitter web has spawned so many “esoteric” right wing freaks, but there’s no appropriate sneer-space for them. I’m talking redscare-ish, reality challenged “culture critics” who write about everything but understand nothing. I’m talking about reply-guys who make the same 6 tweets about the same 3 subjects. They’re inescapable at this point, yet I don’t see them mocked (as much as they should be)
Like, there was one dude a while back who insisted that women couldn’t be surgeons because they didn’t believe in the moon or in stars? I think each and every one of these guys is uniquely fucked up and if I can’t escape them, I would love to sneer at them.
(Credit and/or blame to David Gerard for starting this. Apologies for not getting the previous one up - my old laptop died)
The OpenStax textbook covers the development of the general equations of the various conic sections. If the Stewart book covers that in such detail, it must be jammed into the appendices or exercises someplace. I’ll have to find the time to go over that, at least; I still don’t have a great intuition for hyperbolas.
Yes, this looks like what I need to understand the negative j term in the cross product formula. Cambridge looks to have the 3rd edition of Boas’ book up for download, so I have a copy now. We’ll see how well I comprehend it, I feel like I’m missing the concept of index permutation to really understand the Wikipedia article.
I don’t know how much traffic we’d get if we tried to cultivate a math discussion here. I did make an account on Mathstodon too and perhaps I should spend more time there. Tutoring at this level is sparse, at least at a community college. There’s one tutor for my class available via Zoom, and the instructor himself is apparently teaching 5 classes when he’s only under contract for three. If I signed up for 5 classes as a student, I’m sure I’d be setting off all sorts of alarm bells in the registration department, if they even let me go through with it.
The Levi-Civita symbol is, in programming lingo, a function that takes three arguments:
epsilon(i,j,k)wherei,jandkare integers that label the coordinate axes. Let 0 stand for the x axis, 1 for the y and 2 for the z. Thenepsilon(0,1,2)equals 1. If we swap the values of any two arguments, we flip the sign: e.g.,epsilon(1,0,2)evaluates to -1. Now, swap again:epsilon(1,2,0)must change sign again, so it evaluates to 1. But the sequence 1,2,0 is just the original sequence 0,1,2 read cyclically from a different starting point. In this way, we can work out what the value of theepsilonfunction is for any input. When the inputs are all different, the output is either 1 or -1, depending on whether the input sequence is “in order” or “in reverse order”. Write the numbers 0, 1 and 2 around a circle. Read clockwise, and you get one output; read counterclockwise, and you get the other. If two inputs are the same, thenepsilonmust evaluate to zero, because, for example,epsilon(0,0,1)with the first two inputs swapped isepsilon(0,0,1)again, meaning that the output must be minus itself.