I have owned two 2TB external hard drives for some time, and I lately was seeking new storage devices. Three weeks ago, I bought a #MyBook (8TB #HDD) and a #SanDisk #portable (2TB #ssd with $300 in total from #WesternDigital. They seem decent!
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This article gives the formula for the normal vectors of a surface defined by a scalar field on . The normal vector of the graph of the function at is . This also provides us a way to recover a scalar field from the normal vectors of its graph: normalizing the vectors so that the last component is , and then integrate the rest components.
It is Feb 29 today. The date appears once for as long as 4 years!
Monkey-patching is a powerful tool in programming. In this article, I used techniques of Ruby metaprogramming to define a series of methods
def_before, etc. to help monkey-patching. They look graciously in that we can use it to shorten the codes for monkey-patching (avoiding aliasing and repeating codes).
I have been using Siteleaf to manage my blog. It is just convenient and amazing.
In this article, I introduce the barycentric coordinates: it is an elegant way to represent geometric shapes related to a simplex. By using it, given a simplex, we can construct a hyperellipsoid with the properties: its surface passes every vertex of the simplex, and its tangent hyperplane at each vertex is parallel to the hyperplane containing all other vertices.
In this article, I try exploring an idea: using complex numbers to combine pairs of canonical variables into complex variables: . It turns out that we can write canonical equations , Poisson brackets , and canonical transformations in these complex numbers. Finally, I show two examples of using them in real problems: a free particle, and a harmonic oscillator.
This is my first blog! I will share interesting things in my life here.
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