Tag：multiplication

Time：2021118
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 + … […]

Time：2021117
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 […]

Time：20201115
CSPS2020 T1 Julian day Give the highest respect (kowtow) to the T1 author. T2 Zoo Give some numbers, guarantee\(x∈[1,2^k1]\)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 […]

Time：20201112
(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, […]

Time：20201029
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 […]

Time：20201022
679. 24 point game Source: leetcode https://leetcodecn.com/problems/24game 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: (84) * (71) = 24 Example 2: Input: [1,2,1,2] Output: false be careful: […]

Time：2020822
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, […]

Time：2020819
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 […]

Time：2020518
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 […]

Time：2020420
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 […]

Time：202028
What is BigDecimal BigDecimalIt can represent a floatingpoint 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 = […]

Time：20191221
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} […]