06. Introduction, installation and simple use of octave

One 、Octave Introduction to

1.1 Octave

• Octave Is a programming language , The purpose is to solve linear and nonlinear numerical problems , Especially good at matrix operation
• Octave by GNU Open source software under the project , Earlier versions were command-line interaction ,4.0.0 The release is based on QT Compiling GUI Interactive interface .
• Octave Syntax and Matlab grammar Very close to , It's easy to put matlab The program is ported to Octave. At the same time C++,QT Equal interface Matlab It is more convenient .
• Octave In order to C++ Standard template library programming ;Octave Have oneself Octave Language Interpreter .
• Octave Can be dynamic plug-in unit expand .Octave The interpreter for is available gnuplot And Grace Generate charts and print .

1.2 Octave Language

• Octave Language is literal translation and structured （ Similar to the second generation BASIC） Programming language , Support a lot of C Language Style standard function function , At the same time, you can use UNIX System call to expand and enhance functions , However, it is not supported to quote The way to pass parameters .
• Octave The core of is a set of built-in matrix operation languages （ Such as four operations ） And loadable functions （ For example, finding the inverse of a matrix inv）, Other function calls that can be implemented on the core language without significantly increasing the performance overhead are generally Octave Script There is a form of （ For example, solving equations fsolve function ）.Octave Interpreter It will automatically handle various types of calls .
• Octave Support data construction , It also supports basic object-oriented Programming , But it is usually regarded as Process oriented Of Programming language To look at .

1.3 Octave And Matlab The relationship between

• Octave Grammar is basically the same as Matlab Agreement , Carefully written code should also be available in Matlab And Octave function . But if you call Matlab tool kit , Generally, you can't directly in Octave Up operation , because Octave The included kit is similar to Matlab Not compatible .

• because Octave In order to GNU General public permit The license , So you can copy freely 、 Circulation and use .Octave But in most class Unix operating system Run in , It can also be found in [Microsoft Windows](https://baike.baidu.com/item/Microsoft Windows) Run in . stay [Mac OS X](https://baike.baidu.com/item/Mac OS X) It is also possible to run in , But the setup is more complicated .

• Octave At first, it was MIMU Matlab And Design , Nature and Matlab There are many same functions . This also makes some Matlab The program can be directly or slightly modified in Octave Up operation , Some software development teams also use compatible syntax , Direct development can be done at the same time Matlab and Octave The program used .

Two 、Octave Installation steps of

1. open octave Official website download address ：https://ftp.gnu.org/gnu/octave/windows/

2. Download the compressed package of the software shown in the figure below and decompress

   

3. Open the decompressed package , And double click to open octave.vbs Installation

   

4. Click Next until the following figure appears , Indicates successful installation

   

3、 ... and 、Octave Simple use

• % Notation ,**== Indicates the equal sign ,~=** Indicates that it is not equal to the symbol

• stay Octave The language in does not end with a semicolon , And the semicolon has another function here , That is, if you don't add a semicolon , Enter will display the result ; If you add a semicolon at the end , The result will not be displayed

• disp( a ): Indicative output a Content function of , The result will be output with or without semicolon

• Command to change the flag ：PS1（）, What is in parentheses , Then what is the future logo number

  >> 1+2
  ans = 3
  >> 1==2
  ans = 0
  >> 1~=2
  ans = 1
  >> a=1
  a = 1
  >> a=1;
  >> a=pi;
  >>disp(a)
  3.1416
  >>disp(a);
  3.1416
  >>PS1('>')
  >1+2
  ans = 3
  >PS1('>>')
  >>