Matlab Tutorials

The commands in the Command Window cannot be saved and executed again. Also, the Command Window is not interactive. To overcome these difficulties, the procedure is first to create a file with a list of commands, save it and then run the file. In this way, the commands contained are executed in the order they are listed when the file is run. In addition, as the need arises, one can change or modify the commands in the file; the file can be saved and run again. The files that are used in this fashion are known as script files. Thus, a script file is a text file that contains a sequence of MATLAB commands. Script file can be edited (corrected and/or changed) and executed many times.

Creating and Saving a Script File

Any text editor can be used to create script files. In MATLAB, script files are created and edited in the Editor/ Debugger Window. This window can be opened from the Command Window. From the

Command Window, select File, New and then M-file. Once the window is open, the commands of the script file are typed line by line. The commands can also be typed in any text editor or word processor program and then copied and pasted in the Editor/Debugger Window. The second type of M-files is the function file. Function file enables the user to extend the basic library functions by adding ones own computational procedures. Function M-files are expected to return one or more results. Script files and function files may include reference to other MATLAB toolbox routines.

MATLAB function file begins with a header statement of the form:

function (name of result or results) = name (argument list)

Before a script file can be executed it must be saved. All script files must be saved with the extension “.m”. MATLAB refers to them as M-files. When using MATLAB M-files editor, the files will automatically be saved with a “.m” extension. If any other text editor is used, the file must be saved with the “.m” extension, or MATLAB will not be able to find and run the script file. This is done by choosing Save As... from the File menu, selecting a location, and entering a name for the file. The names of user defined variables, predefined variables, MATLAB commands or functions should not be used to name script files.

Running a Script File

A script file can be executed either by typing its name in the Command Window and then pressing the Enter key, directly from the Editor Window by clicking on the Run icon. The file is assumed to be in the current directory, or in the search path.

Input to a Script File

There are three ways of assigning a value to a variable in a script file.

1. The variable is defined and assigned value in the script file.

2. The variable is defined and assigned value in the Command Window.

3. The variable is defined in the script file, but a specified value is entered in the Command Window when the script file is executed.

References:

1. 'Matlab An Introduction with Applications', Rao V. Dukkipati

2. 'Matlab Ders Notları', Hasan Korkmaz

3. http://mathworks.com 

If you have any question or need some help, leave a comment below.

Table 3: Trigonometric and hyperbolic functions

Function

Description

sin(x) cos(x) tan(x) asin(x) acos(x) atan(x) atan2(y,x) sinh(x) cosh(x) tanh(x) asinh(x) acosh(x) atanh(x)

Computes the sine of x, where x is in radians. Computes the cosine of x, where x is in radians. Computes the tangent of x, where x is in radians. Computes the arcsine or inverse sine of x, where x must be between –1 and 1. The function returns an angle in radians between –π/2 and π/2. Computes the arccosine or inverse cosine of x, where x must be between –1 and 1. The function returns an angle in radians between 0 and π. Computes the arctangent or inverse tangent of x. The function returns an angle in radians between –π/2 and π/2. Computes the arctangent or inverse tangent of the value y/x. The function returns an angle in radians that will be between –π and π, depending on the signs of x and y. Computes the hyperbolic sine of x. Computes the hyperbolic cosine of x. Computes the hyperbolic tangent of x. Computes the inverse hyperbolic sine of x. Computes the inverse hyperbolic cosine of x. Computes the inverse hyperbolic tangent of x.

Function	Description	Example
round(x)	Round to the nearest integer .	>> round(20/6) ans = 3
fix(x)	Round towards zero .	>> fix(13/6) ans = 2
ceil(x)	Round towards infinity	>> ceil(13/5) ans = 3
floor(x)	Round towards minus infinity	>> floor(–10/4) ans = –3
rem(x,y)	Returns the remainder after x is divided by y	>> rem(14,3) ans = 2
sign(x,y)	Signum function. Returns 1 if x > 0, –1 if x < 0, and 0 if x = 0.	>> sign(7) ans = 1

Function

Description

conj(x) angle(x) real(x) imag(x) abs(x)

Computes the complex conjugate of the complex number x. Thus, if x is equal to a + ib, then conj(x) will be equal to a – ib. Returns the phase angles, in radians, for each element of complex array Z. Computes the real portion of the complex number x. Computes the imaginary portion of the complex number x. Computes the angle using the value of atan2(imag(x), real(x)); thus, the angle value is between –π and π.

Horror. Starring Vera Farmiga, Patrick Wilson.Lili Taylor and Ron Livingston. Directed by James Wan. (R. 112 minutes.)

James Wan, for better or worse, seemed destined to be known as "the guy who made 'Saw' " - a film that ushered in the recent era of torture porn cinema.

Never mind that he's directed four movies since then. Never mind that in the hazy memory created by six diminishing sequels, people forget that the original "Saw" was a decent piece of filmmaking. (With less torture than you remember.) Wan was on track to endure a lifetime of sideways looks when he got introduced at parties.

If there's any fairness, he'll now be known as "the guy who made 'The Conjuring.' " The horror movie is artfully crafted from the first scares to the closing credits, with a bold retro vibe. But while its closest cousins are "The Exorcist" and the original "The Amityville Horror," Wan understands that modern audiences have short attention spans. The scares here begin in the pre-credits sequence, and barely let up until the end.

The throwback horror genre has been percolating for years in art houses - most notably with talented young Ti West's "The House of the Devil" and "The Innkeepers." Although West prefers a minimalist approach with a slow build, Wan aims for a more epic style.

"The Conjuring" introduces us quickly to Ed and Lorraine Warren (Patrick Wilson and Vera Farmiga), demonologists who believe in the occult, but understand that most events are easily explained hoaxes. Next we meet the Perron family - Carolyn, Roger and their five girls. With their 1970s clothing and sensibilities, the family is recognizable and realistic, with seasoned Ron Livingston and Lili Taylor in parental roles.

The Perrons have invested too much in an old house, which they gradually learn is haunted by spirits who mean to do them harm. They quickly hook up with the Warrens, who want evidence of the paranormal events before calling in an exorcist. The Perrons agree, after being told that these demons will follow them if they leave. The tale is tied together well - at no point does the plot require anyone to make idiotic decisions in the name of narrative momentum.

Wan's boldest move is his reliance on practical effects, which enhance the 1972 setting. A storm of crows looks more like something from "The Birds" than a modern movie apocalypse. Demons are clearly played by made-up actors. The postproduction digital effects bill couldn't have topped the low six figures - and yet nothing feels skimpy.

The weakness of "The Conjuring" is repetition. There are multiple sequences where a Perron lights the basement with matches, sleepwalks or investigates an armoire, and scenes start to blend together in the 112-minute run time. (The emotionally satisfying ending makes up for minor editing issues.)

Although the budget was likely modest, attention to detail is rich. The musical score sets a menacing tone and is also an effective tease, changing things up to avoid tipping off the audience. As action builds, the camera work seems to get a little shakier and rise to impossible angles, as if the demons are handling the cinematography as well.

The actors are all committed to Wan's vision, but Taylor stands out, giving everything to a complex and constantly shifting role. Writers Chad and Carey Hayes are also assets, resisting the horror movie urge to overexplain. They craft memorable scenes, but also include mystery, ensuring that new things will be discovered upon repeat viewings.

There are two kinds of people who won't like this film: those who hate all horror movies, and a less mature crowd not ready to experiment beyond the cheaper thrills of the "Paranormal Activity" or "Final Destination" templates. (That latter group doesn't trust mainstream movie reviews, so this glowing take should provide adequate warning.)

As the critic in charge of putting together this publication's summer movie preview, I barely considered "The Conjuring" worthy of mention. That was clearly a mistake. I'd be shocked if we see a better horror film in 2013.

source:http://www.sfgate.com

Peter Hartlaub is The San Francisco Chronicle's pop culture critic. E-mail:phartlaub@sfchronicle.com Twitter: @PeterHartlaub