Lecture: Computer as a formal executor of algorithms. Computer as a formal executor of algorithms Presentation on the topic of a computer as an executor of commands

Understand that a computer is a formal executor of programs.

Learn talk about the computer as a universal performer, using computer science terms.

Understand

A computer can execute an algorithm if the algorithm is written in one of the programming languages. An algorithm written in one of the programming languages ​​is called program.

The program must be entered into the computer's memory and launched for execution. The program is then automatically executed by the computer. Therefore, they say that the computer is the executor of algorithms.

An object can be called an algorithm executor if it has the following properties:

The computer performer does not know or understand anything. It formally executes a program, that is, a sequence of commands that are part of its command system and written for it in a special programming language.

The computer never asks "Why?" and for what?". He does not refuse to carry out commands that are part of his command system. Therefore, the computer is called the formal executor of algorithms.

A person can also be a formal performer. As a rule, a person understands what he is doing and why, so he can refuse to carry out commands that he knows how to carry out, but does not consider possible.

A person may not perform an action for moral reasons or for his own safety. For example, a person may refuse to offend the small or weak, jump from a life-threatening height, and so on. That is, he can do it, but he doesn’t want to.

As we have already said, a computer is called universal performer, since it can process data different types: sound, text, numeric, graphic.

A computer can also be called a universal performer because it can be used by different people: mathematicians, writers, doctors, engineers, teachers, students, schoolchildren and even small children. All this is possible, since there are many different programs in the computer’s memory.

Some programs control the computer itself. This system programs. Other programs help create and edit information objects (texts, pictures, diagrams, numbers, etc.). Such programs are called application programs. There are other types of programs.

Complete

Action plan

1. Compare the human performer and the computer performer using the table.

1. Write a short story based on the results of your analysis of this table.
2. Create a table and story in a text editor.
3. Save the file under the name “Artists” in the “My Portfolio” folder.

Main

• A computer can automatically, that is, without human intervention, execute a sequence of commands - a computer program.
• The computer is a universal performer. It is used to process different types of data (text, graphic, sound, numerical), and can be used by people of different professions.
• The computer executor's command system is a list of commands that the computer can execute.

Know

1. What is the difference between a human performer and a computer performer?
2. Can a computer process data if there are no programs in its memory?
3. What devices allow a computer to execute programs?
4. Will a computer execute a program written in Russian? Why?
5. Why is a computer called a formal executor?

Be able to

Complete the tasks in workbook No. 2.

Complete the tasks for the paragraph from the MIND section of the CD on your computer.

At your leisure, read the text “Areas of Computer Application” in the book “Expand Your Horizons.”

Now we know

• A model is a substitute for the original object. An original object is an object of reality.
• The model may be similar to the original object (toy, sculpture, painting, photograph) or may be completely different from it (text, diagram, number).
• The goals of creating a model are to study an object, save information about the observed object, transfer it to other people or show what an object that does not yet exist will look like, and others.
• The model must reflect the properties of the object that are significant from the point of view of the purpose of modeling.
• An algorithm is a sequence of commands that describes the solution to a problem. An algorithm is a model for solving a problem.
• The object that executes the algorithm is the executor of the algorithm.

We have learned

• create linear and branching algorithms for solving simple problems;
• determine and name the forms of writing the algorithm. Present algorithms in text and graphic forms;
• distinguish linear algorithms from branching algorithms;
• compile a list of commands for a specific performer;
• talk about the computer as a universal formal performer, using computer science terms.

Terms to remember

• Algorithm
• Replacement of the original object
• Algorithm executor
• Modeling
• Model
• Original object
• Action plan
• Robot
• Executor command system
• Purpose of modeling

Let's consider the process of managing an information process in which text is selected as the managed object. In other words, let's consider the information process associated with editing (changing the state) of the text.
Firstly, in order to transform text, there must be someone or something that performs these transformations. In other words, it is necessary executor these transformations.
Secondly, the text conversion process must be broken down into separate operations, which must be written as separate teams to the performer. Each performer has a certain set , command system , which he can accomplish. In the process of editing text, various operations are possible: deleting, copying, moving or replacing its fragments. The text editor must be able to perform these operations.
Third, must be defined initial state of the object, in this case the text, and its required final state(purpose of transformation).
We will say that an information process that has all the properties listed above is called algorithm . An executor can execute an algorithm if the algorithm's commands are included in the executor's command system.
For example: the user needs to edit the text as follows:

1. Select characters from 1 to 15.

2. Cut this fragment and place it in the buffer.

3. Place the cursor at the position after the 7th character.

4. Insert the cut text fragment.

The user can perform this algorithm formally. The user, while executing the algorithm on the computer, will press keyboard keys, and when working with graphical interface use the mouse to activate certain buttons, menu items, etc. In fact, the user will give commands to objects of the Windows&Office software environment, which will performers algorithm.

Algorithmic programming languages. Performance information process in the form of an algorithm allows you to assign it automatic execution of various technical devices, among which the computer occupies a special place. In this case, they say that the computer executes a program (a sequence of commands) that implements an algorithm in some programming language.

14 Basic concepts of algorithmization: formal and informal executors of algorithms.

Executor- this is an object (person, animal, technical device) capable of executing a certain set of commands.
Commands that can be executed by a specific performer form executor command system(SKI).

The class of performers is unusually diverse. First of all, it distinguishes two types of performers: formal And informal. A formal performer always performs the same command in the same way. An informal executor can carry out a command in different ways.

For example, when you repeatedly listen to a disc with your favorite melodies, you can be sure that they are reproduced by the player (the formal performer) in the same way. But it is unlikely that any of the singers (informal performers) will be able to perform a song from their repertoire in exactly the same way several times.

As a rule, a person acts as an informal performer. Formal performers are predominantly technical devices. A person in the role of an informal performer is responsible for his own actions. The object that controls him is responsible for the actions of the formal executor.

Control- this is the process of purposeful influence of some objects on others.

Performers are objects of management. You can manage them by creating an algorithm for them.

Algorithm- this is an accurate description of the sequence of actions intended for a specific performer aimed at solving the task.

Algorithms can be written as a table, a numbered list in natural language, or depicted using a flowchart. Program is an algorithm written according to the rules of a language understandable to the computer performer.

15 Algorithmic designs: linear, branching, loops

The appearance of algorithms is associated with the origins of mathematics. More than 1000 years ago (in 825), a scientist from the city of Khorezm, Abdullah (or Abu Jafar) Muhammad bin Musa al-Khorezmi, created a book on mathematics in which he described ways to perform arithmetic operations on multi-digit numbers. The word algorithm itself arose in Europe after the book of this mathematician was translated into Latin.

Algorithm– a description of a sequence of actions (plan), the strict execution of which leads to the solution of the task in a finite number of steps.

You constantly come across this concept in various areas of human activity (cookbooks, instructions for using various devices, rules for solving mathematical problems...). Usually we perform habitual actions without thinking, mechanically. For example, you know well how to open a door with a key. However, in order to teach this to your child, you will have to clearly explain these actions themselves and the order in which they are performed: 1. Take the key out of your pocket. 2. Insert the key into the keyhole. 3. Turn the key counterclockwise twice. 4. Remove the key.

If you look around carefully, you will find many algorithms that we constantly carry out. The world of algorithms is very diverse. Despite this, it is possible to identify the general properties that any algorithm has.

Properties of algorithms: 1. Discreteness (the algorithm must consist of specific actions following in a certain order); 2. Determinism (any action must be strictly and unambiguously defined in each case); 3. Finiteness (each action and the algorithm as a whole must be able to be completed); 4. Massiveness (the same algorithm can be used with different source data); 5. Efficiency (no errors, the algorithm should lead to the correct result for all valid input values).

Types of algorithms: 1. Linear algorithm(description of actions that are performed once in a given order); 2. Cyclic algorithm (description of actions that must be repeated a specified number of times or until the task is completed); 3. Branching algorithm (an algorithm in which, depending on the condition, either one or another sequence of actions is performed) 4. Auxiliary algorithm (an algorithm that can be used in other algorithms by indicating only its name).

For a more visual representation of the algorithm, it is widely used graphic form - block diagram, which is composed of standard graphic objects.

Stages of creating an algorithm: 1. The algorithm must be presented in a form understandable to the person who develops it. 2. The algorithm must be presented in a form understandable to the object (including a person) who will perform the actions described in the algorithm.

The object that will execute the algorithm is usually called the executor.

Executor- the object that executes the algorithm.

Ideal performers are machines, robots, computers...

The executor is able to execute only a limited number of commands. Therefore, the algorithm is developed and detailed so that it contains only those commands and structures that the performer can execute.

The performer, like any object, is located in a certain environment and can only perform actions allowed in it. If the executor encounters an unknown command in the algorithm, the execution of the algorithm will stop.

The computer is an automatic executor of algorithms.

An algorithm written in a computer-readable programming language is called a program.

Programming is the process of writing a program for a computer. For the first computers, programs were written in the form of a sequence of elementary operations. It was very labor-intensive and ineffective work. Therefore, special programming languages ​​were subsequently developed. Currently, there are many artificial languages ​​for writing programs. However, it was never possible to create an ideal language that would suit everyone.

Control questions. What is the difference between a formal performer and an intellectual one? What is NMC? Who proposed such a system? What are the features of executing a program in NML on a computer? What is JPVU? Features of executing a computer program written in LPW? Why can a computer be called a formal performer?

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Algorithm

Download presentation Execution of algorithms by computer.ppt

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