Matlab 教程 仅供学习参考用代码.rar

# MATLAB MATLAB Tutorial This tutorial is for beginners who wants to learn MATLAB. Let's begin with commands. #### Course Contents This course describes about the following topics. 1. Course Overview Familiarize yourself with the course. - Course Overview 2. Commands Enter commands in MATLAB to perform calculations and create variables. - Entering Commands - Storing Data in Variables - Using Built-in Functions and Constants - Desktop Overview 3. Vectors and Matrices Create MATLAB variables that contain multiple elements. - Manually Entering Arrays - Creating Evenly-Spaced Vectors - Array Creation Functions 4. Importing Data Bring data from external files into MATLAB. - Saving and Loading Variables - Import Tool 5. Indexing into and Modifying Arrays Use indexing to extract and modify rows, columns, and elements of MATLAB arrays. - Indexing into Arrays - Extracting Multiple Elements - Changing Values in Arrays 6. Array Calculations Perform calculations on entire arrays at once. - Performing Array Operations on Vectors 7. Calling Functions Call functions to obtain multiple outputs. - Obtaining Multiple Outputs from Function Calls 8. Obtaining Help Use the MATLAB documentation to discover information about MATLAB features. - Obtaining Help 9. Plotting Data Visualize variables using MATLAB's plotting functions. - Plotting Vectors - Annotating Plots - Plots Tab 10. Review Problems Bring together concepts that you have learned with a project. - Project - Electricity Usage - Project - Audio Frequency 11. MATLAB Scripts Write and save your own MATLAB programs. - The MATLAB Editor 12. Logical Arrays Use logical expressions to help you to extract elements of interest from MATLAB arrays. - Logical Operations and Variables - Combining Logical Conditions - Logical Indexing 13. Programming Write programs that execute code based upon some condition. - Decision Branching - For Loops 14. Final Project Bring together concepts that you have learned with a project. - Project - Stellar Motion - Project - Stellar Motion (Script) ### What is MATLAB ..? MATLAB (matrix laboratory) is a multi-paradigm numerical computing environment and proprietary programming language developed by MathWorks. ... Although MATLAB is intended primarily for numerical computing, #### Download & Installation: Download the latest MATLAB from [Download MATLAB](https://in.mathworks.com/downloads/web_downloads) and install it as per your operating system. To get free trail for limited days, please register with your email in MATLAB website. ### Course Overview This explains about MATLAB. ### Entering Commands - You can execute commands by entering them in the command window after the MATLAB prompt (>>) and pressing the Enter key. - Unless otherwise specified, MATLAB stores calculations in a variable named **ans**. - The equals sign (=) in MATLAB is the assignment operator, meaning that the expression on the right of the equals sign is assigned to the variable on the left. So, when you enter x = 3+4, MATLAB first evaluates 3+4 and then assigns the result (7) to the variable x. - Notice that the Workspace window (on the right) shows all the variables currently in the workspace. - Adding a semicolon to the end of a command will suppress the output, though the command will still be executed, as you can see in the Workspace. When you enter a command without a semicolon at the end, MATLAB displays the result in the command window. - You can recall previous commands by pressing the Up arrow key on your keyboard. Note that the Command Window must be the active window for this to work. - When you enter just a variable name at the command prompt, MATLAB returns the current value of that variable. ##### Storing Data in Variables - You can name your MATLAB variables anything you'd like as long as they start with a letter and contain only letters, numbers, and underscores **_**. 3sq = 9 ↑ Error: Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error. To construct matrices, use brackets instead of parentheses. Did you mean: sq = 9 ? - Try clearing all variables by entering the command **clear** - **clear** command removes workspace variables, and **clc** clears the Command Window. ##### Using Built-in Functions and Constants - Info: MATLAB contains built-in constants, such as pi to represent π. a = pi a = 3.1416 Also, although only four decimal places are shown for π, it is represented internally with greater precision. x = pi/2 1.5708 - MATLAB contains a wide variety of built-in functions, such as abs (absolute value) and eig (calculate eigenvalues). a = sin(-5) a = 0.9589 another example x = sin(10) Note that MATLAB uses parentheses to pass inputs to functions, similar to standard mathematical notation. - Now try using the **sqrt** function to calculate the square root of -9. Assign the result to a variable named z. z = sqrt(-9) z= 0.0000 + 3.0000i - Note that the solution contains the imaginary number, i, which is a built-in constant in MATLAB. You can now move to the next section, or, if you are interested, explore a sampling of some of the other built-in functions in MATLAB (linked below). [Elementary math](http://www.mathworks.com/help/matlab/elementary-math.html) [Descriptive statistics](http://www.mathworks.com/help/matlab/descriptive-statistics.html) [Linear algebra](http://www.mathworks.com/help/matlab/linear-algebra.html) ### Vectors and Matrices #### Manually Entering Arrays - All MATLAB variables are arrays, meaning that each variable can contain multiple elements. A single number, called a scalar, is actually a 1-by-1 array, meaning it contains 1 row and 1 column. Create a variable named x with a value of 4. x=4 x= 4 - You can create arrays with multiple elements using square brackets. >> x = [3 5] x = 3 5 Create an array named x with two elements in a single row: 7 and 9 >> x = [7 9] x = 7 9 - When you separate numbers by spaces (or commas), MATLAB combines the numbers into a row vector, which is an array with one row and multiple columns (1-by-n). When you separate them by semicolons, MATLAB creates a column vector (n-by-1) >> x = [1;3]. Now create an array named x with two elements, 7 and 9, in a single column. Try recalling the previous command and changing the space between the numbers to a semicolon (;). >> x [7;9] x = 7 9 - Now try creating a 1-by-3 row vector named x that contains the values 3, 10, and 5 in that order. >> x = [3 10 5] x = 3 10 5 - Now try creating a 3-by-1 column vector named x that contains the values 8, 2, and -4 in that order. >> x = [8;2;-4] x = 8 2 -4 - You can combine spaces and semicolons to create matrices, which are arrays with multiple rows and columns. When entering matrices, you must enter them row by row. >> x = [3 4 5;6 7 8] x = 3 4 5 6 7 8 Try creating a matrix named x with the values shown below. 5 6 7 8 9 10 >>x = [5 6 7;8 9 10] x = 5 6 7 8 9 10 - In MATLAB, you can perform calculations within the square brackets. >> x = [abs(-4) 4^2] x = 4 16 Try creating a 1-by-2 row vector named x that contains **sqrt(10)** as its first element and **pi^2 (π2)** as its second element. >> x = [sqrt(10) pi^2] x = 3.1623 9.8696 #### Creating Evenly-Spaced Vectors - It is common to create vectors containing evenly s