Integration – Basic application of Cauchy's integral sentence

My book (Saff / Snider, page 195) says:

The integral $$ int_ {| z | = 2} frac {e ^ z} {z ^ 2 – 9} = 0 $$

because of the Cauchy theorem since $ frac {e ^ z} {z ^ 2 – 9} $ is analytic everywhere $ z = pm 3. $ And there are these points outside $ | z | = 2 $, it is $ 0 $ after the sentence.

Q1: The domain of $ frac {e ^ z} {z ^ 2 – 9} $ is $ D = C – { pm 3 } $ and is not connected easily, how do you apply the sentence?

Q2: If I look at it in real terms, it's not even continuous $ D = C – { pm 3 } $, I assume analytically in the sense of Cauchy-Riemann, that it requires local analyticity (at a certain time) in contrast to the entire domain?

Note: I am not referring to the Cauchy integral formula. I'm referring to the first one everyone learns ($ f in H (D) implies int_C f = 0 $)

Can I enter the UK without my husband if we stated in our visa application that we were traveling together?

My husband and I will travel to London with my children to attend a wedding ceremony. We will travel on different dates every 10 days. So, do we have to specify our dates when applying for a visa? Even if we include the same data in our application, I may be asked by the Immigration Department why I come to London without it?

design – application that checks URLs from different locations

I am creating an application that monitors the availability of hosts / IP addresses. I use Laravel + VueJS.

Therefore, the app should check many URLs every minute and save them in db http responses. I've never worked with highload before, so I'm struggling a bit.

The thing is: I can save my application to a VDS, run queues using Redis, and run asynchronous jobs. It works for some URLs.


  1. I have no idea how to scale that. For example, when I talk about load balancers, they are used when users make a lot of requests, in my case, it's cronjob, running Linux and running PHP processes.

  2. More importantly, how should the architecture be constructed if I have to check the same URL in different places (like US, Europe, China, etc.)? Of course, I need a lot of servers, but I have no idea how to connect them.

Expected workload: Marking 100,000 requests per minute

finder – assign nothing but default, which opens with the application

Usually I have a bunch of audio files (.mp3) with my music and some other non-audio files (.asd) in the same directory. To quickly play music, I simply select all in the finder and press cmd + o to open them in my standard application (vlc). The ASD files are also opened, but I never want to open them. They are used by the ableton live application, but are not intended to be opened.

is it possible to assign "nothing" as the default application for .asd files? I think maybe with defaults or another command line trick, if necessary.

android – Does a thread in a mobile game serve the same purpose as a view model in a mobile application?

I'm trying to improve my understanding of the coding differences and similarities between mobile phones game Design and mobile app Design for Android devices with Java / Kotlin.


A good design principle in mobile app design is Separation of Concerns, where the app has any number of different classes to serve different purposes. A design architecture divides these concerns into two classes, the "view model" and the "UI controller" (where the UI controller is an activity or a fragment).

The view model should contain code that contains data and makes logical decisions with these data. The UI controller is used to draw this data on the screen of the device and to receive input and operating system events.


In mobile game design, I saw an Activity class, a GameView class (which implements SurfaceView), and a thread subclass. The activity instantiates the GameView class and places the GameView class in its view hierarchy setContentView(GameView(this)), This is different from what the design of mobile apps is setContentView(R.layout.layout_xml_file) is used to provide views

Bitmaps can be drawn on the surface of the GameView object. The GameView object manipulates this interface using surface-specific callback functions much as the UI controller manipulates lifecycle status using lifecycle-specific callback functions. The GameView object also handles user input, such as the UI controller.

The GameView and the UI controller obviously have the same roles.


  • Does a thread in a mobile game have the same purpose as a view model in a mobile app?
  • If not, where should the data and logical decisions go? Are you going to the different bitmap classes?
  • If bitmap classes have the same function as view models, how do they make logical decisions (ie, a Mario object collects a coin object)?

Design Help in designing a complex pricing application and its database

I need to develop a web application to calculate the aviation fuel prices for airlines

It is based on complex calculations. There are many calculated data based on other calculated data
What is really blocked is that there are many calculations. Please let me know how I can use all these calculations to design a database and how to design an application with complex price calculations. Are there any best practices or design patterns?

My team members are not used to these types of projects.

It should be known that the calculation according to my information takes place in several steps.

For step 1:

The user must specify:

  • Decade (the price is calculated every 10 days).
  • the FOB price.
  • the selling price (is that of the marketing committee of
    the Company ).

For step 2:

Determine the exchange rate.

For step 3:

The calculation of margins and deduction of the applied margin for the airline.

For step 4:

From the data of step 2, another price is called base Price be well calculated

For step 5:

From the data of steps 1, 2, 3 and 4 and according to the following criteria, the final price calculation for aviation oil is calculated:

  • the amount of aviation oils
  • the national and international airline
  • Boundary zone of the fuel storage.
  • Type of flight (scheduled and special flights).

gnome – How do I display a notification from a Python3 application on the Ubuntu 18.04 desktop?

If an application has an error and needs to view it as a hint, Ubuntu 18.04 will first flash the note below the clock in the desktop control panel (notification pop-up) and save it in the notification area.

How do I display a hint from my python3 application the same way?