• ## Leetcode Weekly – 174 – 1

Time：2020-9-21

1337. K line with the weakest combat effectiveness in the square array Hi, everyone. I’m a pig. Welcome to the weekly leetcode quiz of the “baby can understand” series. This is the first question in issue 174 and 1337 in the list of topics – “K line, the weakest fighting force in the square array.” […]

• ## Automatic driving positioning system Kalman filter

Time：2020-9-15

Kalman filter is an ideal method to deal with continuously changing dynamic uncertain systems. Because of its small memory consumption (no need to record historical state) and fast running speed, it is widely used in real-time multi-sensor fusion system of robot. What can we do with a Kalman filter Let’s first look at a simple […]

• ## Automatic driving positioning system unscented Kalman filter

Time：2020-9-12

Unscented Kalman filter is another way to solve nonlinear Kalman filter. It uses unscented transform to solve the problem of nonlinear transformation of probability distribution. Unscented Kalman filter does not need to calculate Jacobin matrix like extended Kalman filter, and it can obtain more accurate nonlinear processing effect under the condition of approximately the same […]

• ## Autopilot positioning system – vehicle attitude representation based on basic knowledge

Time：2020-9-11

Vehicle position and attitude is a basic problem in automatic driving. Only when the vehicle position and attitude are solved can the various modules of automatic driving be associated. The position and attitude of the vehicle are generally output by the positioning module of automatic driving. Taking Apollo as an example, the definition of vehicle’s […]

• ## C practical exercises 38

Time：2020-9-5

Title:Find the sum of diagonal elements of a 3 * 3 matrix Program analysis:Using double for loop control input two-dimensional array, and then a [i] [i] accumulation output. example: #include #define N 3 int main() { int i,j,a[N][N],sum=0; Printf (“please input matrix (3 * 3): \ n”); for(i=0;i The output results of the above examples […]

• ## Start from 0 machine learning neural network reverse BP algorithm!

Time：2020-8-18

The project has been so busy in recent month that I finally found time to finish writing the basic idea of BP algorithm. Let’s talk about the derivation of formula in the next article. 1、 Cost function of neural networks Neural network can be regarded as the combination of complex logistic regression, so similar to […]

• ## Unsupervised learning algorithm

Time：2020-8-13

This article starts with the official account number: RAIS, click direct attention. preface This series of articles are the reading notes of “deep learning”. You can refer to the original book and read it together for better effect. Unsupervised learning algorithm It is a kind of unsupervised learning method. It is too abstract. There is […]

• ## Machine learning — gradient descent method

Time：2020-8-7

Notation： m=number of training examples n=number of features x=”input” variables / features y=”output”variable/”target” variable $$(x^{(i)}，y^{(i)})$$ = the ith trainging example $$h_\theta$$ = fitting function 1、 Gradient descent (main) among$$h_\theta(x)=\theta_0+\theta_1x_1+…+\theta_nx_n=\sum_{i=0}^{n}{\theta_ix_i}=\theta^T$$ Suppose the loss function is$$J(\theta)=\frac{1}{2}\sum_{i=1}^{m}{(h_\theta(x)-y)^2}$$ ， To minimize the $$J(\theta)$$ main idea: Initalize $$\theta$$ (may $$\theta=\vec{0}$$) ,then keep changing $$\theta$$ to reduce $$J(\theta)$$ ,untill minimum Gradient […]

• ## Basic knowledge of graph theory (3)

Time：2020-8-5

This article is published in the official account of the self. The original is written by Lee, and has been authorized by the original author. This issue brings you the last part of the summary of the basic knowledge of graph theory. Most of the materials for the production of slides come from the Internet, […]

• ## [Issue 6] two dimensional array you should know before bat interview

Time：2020-8-4

Maybe you’ve seen a lot of interviews that you’ll ask some weird algorithm questions. To be honest, it’s not a shame if you can’t do it by hand tearing red and black trees. It’s OK to have a hard dynamic planning. But I hope you can understand the two-dimensional array related topics. Unlike some strange […]

• ## Evaluation of supervised learning algorithm model

Time：2020-8-2

There are three common methods in the evaluation index of classification model Confusion matrix ROC curve AUC value In the regression model evaluation index, the commonly used methods are as follows: MSE RMSE MAE R2 Confusion matrix In the field of machine learning, confusion matrix is a visualization tool to evaluate the classification model. Definition […]

• ## Linear Algebra — mind map of linear algebra and Its Applications

Time：2020-7-29

Linear algebra, as a basic course of University Science and engineering, has become a basic tool to represent data in machine learning, and its importance is self-evident. When I had studied this course, I didn’t understand many concepts, especially the geometric meaning of linear algebra. Later, in the first half of the semester, I reviewed […]