• Toy Theory: normative dynamics of Yin Yang and five elements


    Recently, a friend asked me if it is possible to use modern physical methods to study Yin Yang and five elements, the content of Chinese traditional culture? At first, I naturally thought that this was nonsense, but on the contrary, if I did not consider the actual situation and thought completely from the perspective of […]

  • [ACM training] DP problem of slope optimization


    Luogu p3195 [hnoi2008] toy packing Topic introduction Link:https://www.luogu.com.cn/prob… shopping spree Solution I (TLE) First write the violent version DP #include <iostream> #include <algorithm> typedef long long ll; #define read(x) scanf(“%lld”, &x) using namespace std; const int N = 50010; ll sumc[N], f[N], n, L; int main() { read(n); read(L); ll c; for (int i = […]

  • [openxml] convert openxml’s elliptical arc arcto to SVG’s elliptical arc


    This article describes how to convert ACTTO of openxml to the arc of SVG (a) Artto for openxml First, the following is an arcto arc of openxml Assuming that our current point is (0,0), the information we know is as follows: Current point coordinates: (x1, Y1) = (0,0) Radius of ellipse: semimajor axis RX = […]

  • Deep learning NS equation


    DiscretizationNet: A Machine-Learning based solver for Navier-Stokes Equations using Finite Volume Discretization https://arxiv.org/abs/2005.08357Solving NS equation with auto encoder NSFnets (Navier-Stokes Flow nets): Physics-informed neural networks for the incompressible Navier-Stokes equationshttps://arxiv.org/abs/2003.06496

  • Leetcode 990. Satisfiability of equation | Python


    990. Satisfiability of equation Title Source: leetcode https://leetcode-cn.com/problems/satisfiability-of-equality-equations subject Given an array composed of string equations representing the relationship between variables, the length of each string equation [i] is 4 and takes one of two different forms: “a = = B” or “a! = B”. In this case, a and B are lowercase letters (not […]

  • How do regular expressions match multiples of 3?


    From Zhihu:http://www.zhihu.com/question/24824487/answer/29109747Author: belleve ^[0369]* ( ( [147][0369]* | [258][0369]*[258][0369]* ) ([147][0369]*[258][0369]*)* ( [258][0369]* | [147][0369]*[147][0369]* ) | [258][0369]*[147][0369]* )* $ Score 488 points, should be able to optimize, but too lazy to do. This regularization is really correct and can be applied to any decimal number instead of cheating as follows. From the following inverse […]

  • JavaScript animation example: curve drawing


    In“JavaScript graphic example: curve equation”In this paper, we give 15 examples of curve equation drawing. According to the curve equation, these curves take a series of angle values in the [0,2 π] interval, calculate the corresponding coordinates of each point according to the given angle value, and then draw the curve by tracing points in […]

  • C practical exercise topic 3


    Title:An integer, after adding 100, is a complete square number, and then 168 is a complete square number. What is the number? Program analysis: Suppose the number is X. 1. Then: x + 100 = N2, x + 100 + 168 = m2 2. Calculation equation: M2 – N2 = (M + n) (M – […]

  • Weighted least squares in Statistical Science


    Today, we will talk about the weighted least squares (WLS), which is based on the ordinary least squares regression (OLS), and is mainly used to solve the heteroscedasticity problem. The general form of OLS is as follows: As we mentioned earlier, OLS has several basic assumptions. One of them is that UI is a random […]

  • The test of Heteroscedasticity


    We talked about heteroscedasticity and how to use graphical method to judge whether there is heteroscedasticity. This article talks about how to use statistical method to judge whether there is heteroscedasticity. There are many statistical methods to test heteroscedasticity. In this section, we only talk about the white test which is more common and commonly […]

  • Regular expression and Mathematics (equation, linear equation)


    The regular expression is as follows: Copy codeThe code is as follows: ^1? $| ^ (11 +?) \ 1 + $can determine the prime number (in the form of N ones, n is the size of the number). For example, 5 to 11111; 3 to 111; 2 to 11.) What is prime?Junior high school. What […]

  • One secret at a time


    One time one secret (OTP) A sequence cipher is called one key at a time, which must meet the following conditions:1. Get the key sequence through the true random number generators_0, s_1, s_2,…;2. Only legitimate communicators know the key sequence;3. Each key sequences_iUse only once.One secret at a time is unconditionally safeIt is proved that […]