Theme 11. Approximation. Linear and quadratic approximations. Spline approximation

Excel is a spreadsheet processor for creating spreadsheets and processing tabular data.

A spreadsheet is a matrix divided by rows and columns, at the intersection of which cells with unique names are formed. Cells are the main element of a table in which data can be input and can be referenced by cell names. Data includes: numbers , dates, time of day, text or symbolic data and formulas.

Data processing includes:

• conducting computations using formulas and functions embedded in the editor;
• construction of diagrams;
• data processing in lists (Sorting, AutoFilter, Advanced Filter, Form, Summary, Summary Table);
• solution of optimization problems (Parameter selection, Search solution, Scripts "what - if other tasks);
• statistical data processing, analysis and forecasting (analysis tools from the add-in "Analysis package").

Excel is not only a means of automating calculations, but also a means of simulating different situations.

Scope of Excel: Planned-Financial and Accounting Estimates, Decision Support Systems (DSS) and other areas of application.

Create a new workbook

                        When you start Excel, the application window displays a new working book, Book 1.

The window has five main areas:

• menu bar;
• toolbar;
• state line;
• line of input;
• worksheet window area.

Basic data processing is carried out using commands from the menu bar. The Standard and Format Toolbars are embedded in the Excel panels, which are arranged below the menu bar and contain certain sets of icons (buttons). The bulk of the icons are designed to execute the most frequently used commands from the menu bar.

A formula line is used to enter and edit values ​​or formulas in cells or charts. The name field is the window to the left of the line of formulas, which displays the name of the active cell. Icons: X, V, fx, located to the left of the line of formulas, are the buttons for canceling, inserting and inserting functions respectively.

The status bar is located at the bottom of the screen. The left side of the status bar indicates the status of the workspace of the spreadsheet (Finish, Input, Edit, Specify). In addition, the left side of the line will briefly describe the results of the executed team. The results of the calculations are displayed on the right side of the status line (when performing automatic calculations using the context menu of the status bar) and the Ins, Caps Lock, Num Lock, Scroll Lock keys are displayed.

The workbook (Excel document) consists of worksheets, each of which is a spreadsheet. If necessary, you can add worksheets or remove them from the book in the book. Button scrolling shortcuts scroll through the labels of the workbook. The extreme buttons scroll through the first and last labels of the workbook. Internal buttons scroll to the previous and next shortcut to the workbook.

Basic concepts of the spreadsheet: column header, line heading, cell, cell name, selection marker, fill marker, active cell, line of formulas, field name, active area of ​​the letter.

The workspace of the spreadsheet consists of rows and columns with their names. Line names are their numbers. Line numbering starts with 1 and ends with the maximum number set for this program. Column names are the letters of the Latin alphabet, originally from A to Z, then from AA to AZ, BA to BZ, and so on.

The maximum number of rows and columns is determined by the features of the program used and the size of the computer's memory, for example, in the Excel spreadsheet 256 columns and more than 16 thousand rows.

The intersection of a row and a column forms a table element that has its own unique address. In order to specify cell addresses, references are used in formulas (for example, A6 or D8).

The cell - the area defined by the cross section of the column and the row of the spreadsheet, has its own unique address. The address of the cell is determined by the name (number) of the column and the name (number) of the line, at the intersection of which is a cell, for example A10. Link is an indication of the address of the cell. Active cell is a highlighted cell whose name is displayed in the name field. The allocation marker is called a semidouble frame around the selected cell. The fill marker is a black square in the lower right corner of the highlighted cell.

The active area of ​​a sheet is an area containing the entered data. In spreadsheets, you can work with individual cells, or with groups of cells that form a block. Block of cells - a group of adjacent cells, determined by the address.

The address of the block of blocks is given by specifying the references of the first and the last of its cells, between which the separator character is put - a colon. If the block has a rectangle, its address is given by the addresses of the left upper and lower lower cells in the block. The block of cells used can be indicated in two ways: either the task from the keyboard of the source and the final cell addresses of the block, or by selecting the corresponding part of the table with the left mouse button. Example cell and block address assignments:

1. The address of the cell, located at the intersection of the column F and line 9, is expressed by the link F9;
2. address of the block formed as part of line 1, - B1: E1;
3. address of the block formed in the form of column C, - C1: C21;
4. The address of the block formed in the form of a rectangle is A3: G10

Working with files

When saving a working book, the dialog box "Save document" opens. In this window you must specify: file name, file type, select disk and folder where the working book will be stored. Thus, a book with incoming work sheets in it is stored in a folder on a disk as a separate file with a unique name. Book files have an xls extension.

To open a workbook, you must select the File / Open command or click on the Open button on the standard toolbar. Excel will display the dialog "Open Document" in it you can select the desired file and click on the Open button.

In order to close the workbook, select the File / Close command, which will close the workbook. To exit Excel, you must select the File / Exit command, or click on the close button in the right side of the title bar of the application window.