Matlab directories

A directory c matlabrxx work will be created where the results of your session will be stored unless you specify differently. There are several commands to manage directories. The cd command changes directory so that cd c changes the directory to c . If the new directory does not exist you must first create it with the mkdir command. It is best not to include a space in the name of the directory. The following code creates a directory called results on the c drive and makes this the current Matlab directory ... 

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. 

MATLAB can keep a diary of a session or parts thereof via the commands diary or diary Junel2, for example, which collects all screen output in a file called diary or Junel2 , respectively, in the current working directory. The command diary off stops the collection of the on-screen information. If the diary on command is given later in the same session, the subsequent screen output will be appended to the previous diary and saved. Please read up on diary by entering help diag. 

When working with MATLAB we advise our readers to first create a separate folder or directory on his/her hard drive that is used exclusively for MATLAB m files, such as one called matlabin, for example. 

By default Matlab will be installed in the directory C matlabrxx on your PC, where xx relates to the edition of the package. You can choose to install elsewhere but at first it is best to stick to the standard directories, which we will assume below. You need some knowledge of DOS directory structure to use the directory commands within Matlab. According to particular combinations of versions of Windows and Matlab there is some flexibility, but keeping to the commands below is safe for the first time user. 

These files store the workspace or variables created during a session. All matrices, vectors and scalars with unique names are saved. Many chemometricians exchange data in this format. The command save places all this information into a file called matlab.mat in the current working directory. Alternatively, you can use the Save Workspace item on die File menu. Normally you wish to save the information as a named file, in which case you enter the filename after the save command. The following code saves the results of a session as a file called mydata in the directory c results, the first line being dependent on the current working directory and requires you to have created this first ... 

In order to access these data in Matlab from an existing file, simply use the load command, remembering what directory you are in, or else die Load Workspace item on die File menu. This can be done several times to bring in different variables, but if two or more valuables have die same names, die most recent overwrite the old ones. 

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. 

Change the current directory in MATLAB (at the top of the command window) to a directory in which you wish to save your work and save it as f.m. 

Step 3 Once the check is made, you can add to the end of every line. Note that to test the function you had to do three things correctly (1) tell MATLAB the name of the function (equil eq) (2) be sure the function was in the working directory (or some place MATLAB would look) and (3) provide a value of x. 

Option 1 Use the set path command to point to an area where you store your programs and data. Add this path to your path directory. When MATLAB looks for a m-file (a program you write), it will look in all these directories, from top to bottom until it finds one with the same name. Then, it will use that m-file. 

This means that q is either an undefined function or an undefined variable. If q is a function or m-file, then MATLAB cannot find it. Check the working directory or use set path and make sure that the path is set to the folder where you stored the m-file and that you have added that path to the list. Do not forget to save your pathlist so that it is there the next time you use MATLAB. If q is a variable, it has not been set or was not transferred correctly. 

Prior to running the programs enclosed in the diskette, the user should copy them into a sub-directory in a hard drive and make sure that the paths of these programs are added to the MatLab worksheet so that they can be executed. 

MATLAB provides main categories of functions. Some of MATLAB s functions are built into the interpreter, while others take the form of M-files. The M-file functions, and in the case of the built-in functions, M-files containing only help text, are organized into directories, each containing the files associated with a category. The MATLAB command help displays an online table of these main categories. 

Two identification examples will be discussed in this section. The parametric model identification is done in MATEAB using the identification toolbox. Let us assume that you have copied the files on your distribution disk to the directory C MatlabR14 work directory. Start Matlab by double clicking the Matlab icon. You are now ready to run the identification examples. 

Open Matlab and set the current directory to your directory. 

MATLAB search path is an ordered list of directories that MATLAB searches to find script and function M-files stored on disk. The MATLAB s path is defined from the File menu via clicking on the Set Path sub-menu, as shown in Figs. 3.1 and 3.2a. 

Alternatively, in case you would like to replace this file by the original file that MATLAB comes with, you can click on the default button shown at the bottom of the Set Path window (see Fig. 3.2a). which will replace the content of pathdef.m by that of the file named restoredefaultpath.m. Both files are found under the directory X Program Files MATLAB R2011a toolbox local . 

NOTE The default directory may change from the aforementioned, based on where the user installs MATLAB and its version. 

After that, save the file as F2C.m. Of course, the F2C.m file has to be saved in a directory that is part of MATLAB s search path. This search path is defined in Sec. 3.2. 

Create the file named qroots.m in your present working directory using the MATLAB m-editor. 

To see the directory path to a file named myf.m, at the MATLAB command prompt you enter ... 

Read the cameraman.tif that is found in the MATLAB installed directory and assign it to an image array, named CamMan. Your task is to create a white box (30 x 30 pixels) anywhere within the image and show the modified image, where the white box appears embossed within the image. Repeat the task and create a black box with a size of 30 x 30 pixels. 

To demonstrate how to import data from another application into the MATLAB environment, let us assume that the experimental data exist in a file sheet such as Excel. The data represent the yearly incoming surface erythemal solar UV radiation dosage (J per cm ) for a clear sky, after modulation due to average cloud cover, as a function of earth latitude. The data were excerpted from M. Ilyas [Climate augmentation of er5 hemal UV-B radiation dose damage in the tropics and global change, Curr. Sci. 93(11) 1604-1608, 2007]. For simplicity, the file was copied to, or moved into, one of the MATLAB search path directories so that it will appear in the Current Folder Window of MATLAB (Fig. 5.1). 

Close the entire MATLAB application and go to the location of the Output folder (as shown in Fig. 11.301 and run the executable file (BMI.exe) created by the MATLAB compiler. A DOS blank screen will pop up, followed by the same GUI we created during the design phase and that was uploaded as a shared resource during the deployment phase. Figure 11.31 shows the results of the execution process. Notice that the Results.txt file is created in the root directory where the application file resides. 

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) ... 

It is important that the search path used by MATLAB is set correctly so that the files may be found from any directory that MATLAB may be running. In the MATLAB Command Window choose File, Set Path. This will open the Path Browser. From the menu of the Path Browser choose Path, Add to Path. Add the directories of your hard disk where the Numerical Methods programs have been installed (the default directory for the WINDOWS installation is C Program Files Numerical Methods Chapterl, etc.). The path should look as in Fig. 2, provided that the default directory was not modified by the user during setup. 

The icon is the command prompt. Anything entered after this is a MATLAB command. The Current Directory window displays folders and files associated with... 

Perhaps the first thing to do when first using MATLAB is to set the Path. The Path is a list of directories that MATLAB searches for files. The default Path is where users usually want to store files and recover them later. A usual place for file storage might be on a thumb drive. Assume that the directory of interest is F MyDocuments MATLAB. To put this directory into the Path and to make it the default directory, go to the File menu and click on Set Path—the following window appears ... 

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