Matlab file types

In the previous sections we have used MATLAB commands that were typed in on the desktop command line, as well as MATLAB commands that invoke special stored MATLAB files, called m files. When starting to work with MATLAB, we advise our users to create a special folder for their personal MATLAB m files once and to continue to use this folder to store personal m files. To access the stored m files from the MATLAB desktop, the user has to point the small desktop window called Current Directory to the personal m file folder. Then all stored m files, as well as all built in MATLAB functions can be accessed, called upon, and used from the command line. All stored personal... 

If this function m file is stored as f unct. m in the current desktop working directory, it can be called and executed in MATLAB by typing funct(3,5,17) or x=3 z=5 k=17 [yy.sign] = f unct (x, z, k) for example. These calls will create the following sequence of outputs. 

Figures and plots can be generated easily via MATLAB. These can be transformed into and stored in many formats, such as MATLAB s generic, , .fig, or as Jpeg, postscript, RAW, TIFF, etc. files as desired. Simply look at the dialogue box that pops up from the save icon of a MATLAB figure. For a quick introduction to MATLAB graphics, type demo matlab graphics and a Help window will open, that lets you choose several clickable graphics demonstrations. We defer further explanations to our relevant graphics codes in later chapters.

These files keep a record of a session. The simplest approach is not to use diary files but just to copy and paste the text of a Matlab session, but diary files can be useful because one can selectively save just certain commands. In order to start a diary file type diary (a default file called diary will be created in the current directory) or diary filename where filename is the name of the file. This automatically opens a file into which all subsequent commands used in a session, together with their results, are stored. To stop recording simply type diary off and to start again (in the same file) type diary on. 

While a sequence of commands in the Command Window can implanent many algorithms, it is awkward if selection (if-then-else) or repetition (e.g., while) logic is involved. The best way to do programming in MATLAB is to construct an M-flle (comparable to a VBA Macro). These are called M-flles since the automatic file type is. m. 

A seript file should have a name that ends in .m , and is run by typing the name of the file (without .m ) after the MATLAB prompt, or by typing the sequenee... 

The advantage of a seript file is that it only needs to be ereated onee and saves the labour of eontinually typing lists of eommands at the MATLAB prompt. 

A script m file in MATLAB does not start with a function. . . declaration as the function m file fzerotryl. m does. A script m file rather consists only of MATLAB commands. See Section 1.2.5 for more details on these two types of m files in MATLAB. 

MATLAB m files can contain any number of MATLAB commands. They are handy for long sets of MATLAB instructions or data and afford easy repeated use and easy modification. There are two kinds of MATLAB m files function and script m files. Script m files such as poly9. m on p. 28 use the data that is defined inside of them and any undefined data is taken from the data (with the proper name) that is currently active on the workspace look at the top left window commonly displayed on the MATLAB desktop for a list of defined variables and their type. Script files overwrite the workspace data as instructed in their code. 

These files are simple text files and may be created in a variety of ways. One way is via die normal Notepad text editor. Simply type in a series of statements, and store diem as a file with extension. m. There are five ways in which diis file can be ran from die Matlab command window. 

Start Matlab, type open together with the name of the. m file, e.g. open myprog.m, and a separate window should open see Figure A.34. In the Tools menu select Run and then return to the main Matlab screen, where the results of the program should be displayed. 

In MATLAB you write computer programs that are called m-files and are saved on your computer. The files can be used at any time by simply typing their name in the command line, and one m-file can use another m-file. You will want to include comments in your m-file that explain what the file does. This is done by inserting a % everything after % on a line is considered a comment. These comments remind you of details when you come back to the program at a later time. 

If the code you wish to check is in an m-file, the first check is to see that all the parameters are passed correctly and have been set in the workspace available to the m-file. The easiest way to do this is to request that the m-file print all the variables you expect to be transferred to the m-file, at the start of the m-file, and check that they are correct. If a variable has not been set, MATLAB wiU give you an error message without running the code. It tells you the line and column where the undefined variable is. The problem is probably improper passing of parameters or incorrect use of the global command or, sometimes, a typing error. 

To change any of those parameters, for example the particle radius to 0.1, the user simply replace R = 0.2 in the USER SUPPLY SECTION to R = 0.1. Next save the file, and then return to the MatLab worksheet and execute the program by simply typing ADSORB 1 A. 

To create an M-file (script type) using the built-in MATLAB m-editor/debugger, go to File menu as shown in Fig. 3.3. click on New (sub-menu), and choose the Script sub-submenu. Alternatively, while activating the MATLAB main window, you may click CTRL+N to open up the m-editor. 

After saving the M-file in MATLAB s search path, type the name of the M-file without extension. Notice that naming is case sensitive. You must be very aware of this issue or you will experience problems with MATLAB. 

To execute the script M-file, simply type the name of the script file, qroots, at the MATLAB prompt ... 

Do not give a script file the same name as a variable it computes, because MATLAB will not be able to execute that script file more than once unless the variable is cleared. Recall that typing a variable name at the command prompt causes MATLAB to display the value of that variable. If there is no variable by that name, then MATLAB searches for a script file having that name. For example, if the variable qroots is created in a script file having the name qroots.m, then after the script is executed the first time, the variable qroots will exist in the MATLAB workspace. If the script file is modified and an attempt is made to run it a second time, MATLAB will display the value of qroots and will not execute the script file. 

Do not give a script file the same name as a MATLAB command or function. You can check to see whether a function already exists by using the which command. For example, to see whether qroots already exists, type... 

Figure 4.1 MATLAB Workspace shows that the creation of image arrays mainly depends on the image color type embedded in the image file itself.

Figure 10.47 shows a portion of the pop-up optimtool Window, in which the user inputs the type of solver to be used by MATLAB the solver (choose fmincon) the algorithm (choose Active set) the objective function file (choose a handle to objecfun function) the derivatives (choose Approximated... 

Figure 10.47 A portion of optimtool Window in which the user decides on the type of solver and algorithm to be used by MATLAB, the objective function file the start point vector, the lower and upper bound vectors the nonlinear constraint function and finally the derivative evaluation method.

Figure 11.18 Defining the dataset for which MATLAB will import the data from Excel sheet. Two string-type global cell vectors are further defined that contain the names and molecular formulas of 188 chemical species. They are made global so that they can be referenced in other sub-modules in GUI vdw.m, the counterpart M-file of GUI vdw.fig.

Data for a person with type 1 diabetes are available as both MATLAB and Excel data files on the book web... 

A MATLAB code, or m-file, is a collection of commands that are executed sequentially. Commands can be mathematical operations, function calls, flow control statements, and calls to the functions and scripts described in Section C.1.4. m-files are written using the MATLAB editor and have names such as my file. m. They are executed from the MATLAB command window by typing the name of the m-file (without the. m). Saving an m-file will avoid many hours of retyping the same commands. 

There are two types of m-files, functions and scripts. A MATLAB function has variables that can be passed into and out of the function. Any other variables used inside the function are not saved in memory when the function is finished. Scripts, on the other hand, save all their variables in the MATLAB workspace. Functions and scripts have names like myfunction.m. The first line of a function must contain a function declaration, using the following format ... 

Commented lines immediately following the function declaration comprise the help file for the function. To obtain information on any function, simply type help function. Some MATLAB functions that are useful for process control include ... 

Typing help alone lists the names of all directories in the MATLAB search path. Also, if you type a directory name in the place of the file name, MATLAB lists contents of the directory (if the directory is a directory in the MATLAB path search and contains a contents.m file) ... 

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