• ## Linear regression: the realization of least square method

Time：2021-1-18

catalog 1、 Linear regression 2、 Least square method 3、 Least square method (vector representation) 4、 Python implementation 1、 Linear regression    given the sample x = (x0, x1, X2,…, xn) described by N attributes,linear modelTry to learn a suitable linear combination of sample attributes to perform the prediction taskf(x) = w1x1 + w2x2 + … […]

• ## Integer ring

Time：2021-1-17

ring Integer ringZ_mIt consists of the following two parts: 1. AssemblyZ_m = ( 0,1,2,…,m )2. Two kinds of operations “+” and “X” make thea, b\in Z_myes: a + b\equiv c\ mod\ m, (c\in Z_m)\\ a\times b\equiv d\ mod\ m, (d\in Z_m) Key features of rings If the result of the addition or multiplication of any […]

• ## CSP-S-2020

Time：2020-11-15

CSP-S-2020 T1 Julian day Give the highest respect (kowtow) to the T1 author. T2 Zoo Give some numbers, guarantee$$x∈[1,2^k-1]$$And different from each other, some conditions are given if there are numbers$$x$$The first$$ai$$Bit is$$1$$Then you have to choose the item$$bi$$，$$bi$$They are different. How many numbers are there$$y$$Satisfaction does not exist$$x=y$$And add$$y$$Post selected$$b$$unchanged. It is easy to […]

• ## On binary (2) – four operations

Time：2020-11-12

(Note:SegmentfaultThe mathematical formula in the article isBUGWhen previewing, it is good. When the article is sent out, it will show that there is a problem. If you have any problem when you read it, you can move on http://www.dubingxuan.com/article/8/ ) Preface In the last article about binary system (1), we spent a lot of space, […]

• ## Using sowteno 2.0

Time：2020-10-29

Tensorflow is Google’s open source artificial intelligence library, which has the most perfect ecological support. It is a necessary tool for the development and scientific research in the field of artificial intelligence.In this paper, under Windows 10, with the help of anaconda, tensorflow 2.0 is installed. tensorflow2.0 install First open anaconda and execute the conda […]

• ## Leetcode 679. 24 point game | Python

Time：2020-10-22

679. 24 point game Source: leetcode https://leetcode-cn.com/problems/24-game subject You have four cards with numbers 1 to 9. You need to determine if you can get 24 by the operation of *, /, +, -, (,). Example 1: Input: [4,1,8,7] Output: true Explanation: (8-4) * (7-1) = 24 Example 2: Input: [1,2,1,2] Output: false be careful: […]

• ## Why normal distribution is so common

Time：2020-8-22

Everyone believes in it (normal distribution): experimenters think it is a mathematical theorem, mathematical researchers think it is an empirical formula.—-Gabriel Lipman This paper is mainly to explain the least squares method, ridge regression and other optimization methods. Normal distribution in life The height of women in life, Let’s say you have 200 blind dates, […]

• ## Least square method and ridge regression lasso regression

Time：2020-8-19

Contents:[TOC] Throw a brick to attract jade If you have just finished a certain exercise, your girlfriend says, “how long are you?”? Then you take a ruler and you want to measure it. Because it is very empty, so the eyes are a little bit dull. After measuring five times, there are five results:18.1cm，17.9cm，18.2cm，17.8cm，18.0cm How […]

• ## Review of basic knowledge of linear algebra

Time：2020-5-18

Review of basic knowledge of linear algebra Machine learning needs some basic knowledge of linear algebra. Matrix: matrix $A= \begin{bmatrix} 1402 & 191\\ 1371 & 821\\ 949 & 1437\\ 147&1448\\ \end{bmatrix}$ $B= \begin{bmatrix} 1 & 2 & 3 \\ 4 & 5 & 6 \\ \end{bmatrix}$ A is a$$4\times2$$The matrix of is composed […]

• ## How to design classes in Java

Time：2020-4-20

2019/12/24   |    The first semester of sophomore year   |Taiyuan University of science and technology      After learning java for the first time, we will find that the difficulty of Java is not that Java syntax is difficult to learn, but that we are hung on the “rope” of how to design classes. This is exactly one of the gaps […]

• ## In depth understanding of the use of BigDecimal

Time：2020-2-8

What is BigDecimal BigDecimalIt can represent a floating-point number of any size with full accuracy. Why use BigDecimal instead of double Talk is cheap, Show me the Code. Example 1: double d1 = 0.3; double d2 = 0.2; System.out.println(“Double:\t 0,3 – 0,2 = ” + (d1 – d2)); float f1 = 0.3f; float f2 = […]

• ## Matrix multiplication optimization

Time：2019-12-21

Preface From Xudong’s blog, I saw a blog: matrix multiplication optimization combined with dynamic programming solution, which is quite interesting. Here’s a reprint [slightly modified]. problem Matrix multiplication satisfies the combination law, but not the commutation law. For example, matrix $a {AB}, B {BC}, C {CD}$are multiplied to get matrix $s {ad}$ \[ S_{ad}=A_{ab} B_{bc} […]