• Good looking loading


    1. Small circular loading with different sizes <!DOCTYPE html> <html lang=”en”> <head> <meta charset=”UTF-8″> <meta http-equiv=”X-UA-Compatible” content=”IE=edge”> <meta name=”viewport” content=”width=device-width, initial-scale=1.0″> <title>Document</title> </head> <body> <div style=”width:100%;height:100vh;display: flex;justify-content: center;background-color: rgb(195, 191, 191);”> <div class=”d1″> <p></p> <p></p> <p></p> <p></p> </div> <div class=”d1″> <p></p> <p></p> <p></p> <p></p> </div> </div> </body> <style> *{ margin: 0; padding: 0; } .d1{ […]

  • Why normal distribution is so common


    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, […]

  • KVO-Key Monitoring


    Keyvalue monitoring means that it can monitor the change of an object’s attribute value. First, in engineering, create a new Person class @interface Person : NSObject @property (nonatomic, copy) NSString *name; @end Introduce the header file “Person” in viewController and start testing the use of KVO – (void)viewDidLoad { [super viewDidLoad]; Person *person = [[Person […]