Here's a requiring a bit of algebra.

For any four non-collinear points A, B, C, and D in three-dimensional space, there is a unique hyperbolic paraboloid H containing the lines AB, BC, CD, and AD (that is, every point on any of these lines is also on the surface of H). Write a program that accepts Cartesian coordinate triplets representing A, B, C, and D and prints an equation in x, y, and z that is satisfied if and only if <x, y, z> is a point on H.

Your program's output may differ from the examples but should be optimised for human readability. Combine like terms, omit terms equal to zero and avoid unnecessary factors (e.g. prefer "x = y" to "2x + 0 = 4y - 2y" even though both describe the same surface).

Example 1 input:
<0, 1, -1>; <1, 0, 1>; <0, -1, -1>; <-1, 0, 1>
Example 1 output:
z = x² - y²

Example 2 input:
<1, 1, 1>; <1, 0, -1>; <-1, 1, -1>; <-1, 0, 1>
Example 2 output:
2y = xz + 1

Example 3 input:
<0, 1, 1>; <0, 1, -1>; <0, -1, -1>; <0, -1, 1>
Example 3 output:
x = 0

@freemo

I see in Mastodon's API there is a call to dismiss a specific notification. Is there a way to do this from the web frontend?

Electoral math, CW for length (3108 characters hidden) 

Here is a which corresponds to the general case of a problem I ran up against recently.

Given a positive integer K and a directed graph G with weighted edges, return a new graph H satisfying all the following conditions, if such a graph exists:

1. G and H contain exactly the same set of vertices.
2. H contains only edges in G, but G may contain edges not in H.
3. A path exists in H of length at most K between each pair of vertices in each direction.
4. No edge can be removed from H while still satisfying condition 3.

Where more than one graph exists satsifying these conditions, return the one with the least total weight. You may assume G does not contain edges with negative weights.

Here is an example G, each triplet representing the <start, end, weight> of an edge:
<1, 2, 40>
<1, 3, 12>
<1, 4, 50>
<2, 1, 84>
<2, 3, 19>
<2, 4, 69>
<3, 1, 25>
<3, 2, 78>
<3, 4, 93>
<4, 1, 75>
<4, 2, 36>
<4, 3, 96>

Your program should produce the following H given the above G and K = 2:
<1, 2, 40>
<1, 4, 50>
<2, 1, 84>
<2, 3, 19>
<3, 1, 25>
<4, 2, 36>

Kyle boosted

@freemo there are two people who i used to follow, who aren't being followed by me any more, who still follow me, and who haven't blocked me.

when i visit their profile from within our instance i'm given the option to cancel a follow request??

Freedom of speech and the Web. Rest CW'd for length (4850 chars hidden) 

Kyle boosted

@mancavgeek As an Admin of I'd like to speak on the record here.

As we make clear in out ToS we dont block other instances but we DO censor. We believe in free speech in the sense that you wont get blocked for simply holding an unpopular opinion. But anyone who attacks others, insults them, or acts aggressive towards others are, and have been banned. We do NOT tolerate racism.

As others have pointed out, none of our users are hateful or racist. On the few cases that happened it resulted in a ban.

I generally suggest people ban instances based on what they do or do not tolerate from their users, rather than some ideological response to some key words in a description.

If anyone in this thread actually knows of an example of any user on QOTO not living up to what I described please let me know, we will take care of them.

@union

Kyle boosted

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