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After giving some thoughts, I think something like GitHub issues can be the ultimate form of a #socialmedia platform. One can conveniently refer to other issues using just owner/repo and issue number. One can use issue templates. One can use Markdown as well as inserting multimedia contents in comments. One can react with an emoji. These features easily beat Reddit and Mastodon. It only misses normal social platform features like exploration and tagging.
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Articles
Relationship between the Gini coefficient and the variance
Both the Gini coefficient and the variance are measures of statistical dispersion. We are then motivated to find the relationship between them. It turns out that there is a neat mathematical relationship between them.
- Categories: economics
- Tags: from zhihu, calculus, probability
Distinguishing all the letters in handwritten math/physics notes
Personally, I have the demand of handwriting math/physics notes, but an annoying fact about this is that I usually cannot distinguish every letter that may be possibly used well enough. In this article, I will try to settle this problem.
- Categories: misc
- Tags: from zhihu, font, tex, handwriting, long paper
手纸本
何为手纸本?
- Categories: literature
- Tags: from zhihu, literary composition, short story, chinese
Introducing bra–ket notation to math learners
Bra–ket notation is a good-looking notation! I am sad that it is not generally taught in math courses. Let me introduce it to you.
- Categories: math
- Tags: from zhihu, quantum mechanics
Even solutions to bound states in an odd number of potential wells
We try solving the even function solutions to the time-independent Schrödinger equation for the potential such that (bound states).
- Categories: physics
- Tags: from zhihu, quantum mechanics
Defend our earth against aliens’ bullets!
The aliens intiated their attack to the earth! They shoot bullets with mass and speed from a far-awar planet. To defend, humans built a field that can repel the bullets. What regions are safe? The answer turns out to be the interior of a circular paraboloid.
- Categories: physics
- Tags: calculus, classical mechanics, kepler problem, from zhihu
This is what will happen after you get a haircut
Denote the length distribution of one’s hair to be , where is hair length, and is time. Considering that each hair may be lost naturally from time to time (there is a probability of for each hair to be lost within time range from to ) and then restart growing from zero length, how will the length distribution of hair evolve with time? It turns out that we may model it with a first-order PDE.
- Categories: math
- Tags: calculus, probability, pde
I want to invent a better way to read numbers
Reading numbers in English is a pain. I want to invent a better way to read numbers!
- Categories: language
- Tags: imagination
The longest all- substring of a random bit string
Given your probability of breaking the combo at each note, what is the probability distribution of your max combo in the rhythm game chart? I considered the problem seriously!
- Categories: math
- Tags: long paper, rhythm game, algorithm, probability
I made this, for the number of days in a week is prime
The number of days in a week is prime, so we cannot utilize weekly periods to help us remember periodical events unless the period is a multiple of 7. However, there may be something that we need to get reminded of which happens once per two days or three days. For example, I wash my hair once per two days and wash my clothes once per eight days. To solve the problem, I wrote a Ruby program to help remind me of those routines.
- Categories: programming
- Tags: selfhosting, linux, ruby
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