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Ben Reiniger @bmreiniger@mathstodon.xyz

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Python versus R? for bioinformatics? What does everyone think?

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What is "one month after January 31"?

- February 28
- March 3
- February
- ??

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Although I long ago dropped out of research , I really love asking working mathematicians to explain whatever it is they are interested in. I have enough general knowledge that they can usually simplify things enough for me to get the gist of their work. Plus, they're usually really enthusiastic about explaining what they do, because most strangers they meet cannot or will not follow!

Great fun to see them light up and have them tell me the metaphors they've developed for their art.

Happy e Day everyone (in the M/D/YY world anyway)!

Not sure how to celebrate...

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You know that trick they teach you to evaluate

\[
\int_{-\infty}^\infty e^{-x^2} dx
\]

Multiply it by itself and change to polar coordinates?

Turns out there's a theorem that this trick doesn't generalise at all! It works for this integral and this integral only! (Modulo some trivial multiplicative constants.)

cs.stmarys.ca/%7Edawson/Poisso

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TIL the changing table has perfect height for a standing desk. Seems obvious in retrospect.

Any other Mathstonautes going to the Joint Math Meetings in San Diego?

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This game is a bit addictive and it's kinda sad whenever humanity goes extinct. But such a warm fuzzy feeling when the colonists end up weird but happy. philome.la/johnayliff/seedship

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A question on a multivariate calculus final: find \((\hat{\imath}+\hat{\jmath})\times(\hat{\jmath}+\hat{k})\)
A surprisingly large number of students answered
\(\begin{vmatrix}\hat{\imath}&\hat{\jmath}\\\hat{\jmath}&\hat{k}\end{vmatrix} = \hat{\imath}\hat{k}-\hat{\jmath}^2. \)

Why? Just "cross product is determinant, these two vectors look two-dimensional, better take a 2x2 determinant"?

[Mathstodon doesn't like \(\ihat, \jhat\)?]

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I've just discovered that if you click the little settingsy thing at the top of the local timeline column, you can click "Pin" to add it as a permanent column.

Not sure why that took me so long. Is it new?

Vi Hart, now Patreon-supported, takes on Halloween leftover Smarties: orientations, combinatorics, graph theory, and a bit of geometric rigidity:

youtube.com/watch?v=4orZQ9Z0WL

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Ben Reiniger boosted

arxivist.com/

Instead of subscribing to particular subjects on arxiv, this might be a nice alternative.

I found out about this from a Google Plus post by Timothy Gowers.

plus.google.com/+TimothyGowers

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This is wonderful - the importance of understanding, accepting, and working through the state of being stuck: mathwithbaddrawings.com/2017/0

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Trying to write up my complete solution of the four dots, two distances puzzle. Remarkably difficult to be concise. Working ...

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@ColinTheMathmo re your "configurations of 4 points with 2 distinct differences" question: I have three layouts: 4 short, 2 long; 3 short, 3 long; 5 short, 1 long. Are there multiple layouts matching those descriptions, or can I get more long than short, or have I finished?