In Matlab

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Under major construction

X = A./B divides each element of A by the corresponding element of B. The sizes of A and B must be the same or be compatible. If the sizes of A and B are compatible, then the two arrays implicitly expand to match each other. For example, if one of A or B is a scalar, then the scalar is combined with each element of the other array.
MATLAB MATLAB is a high-level technical computing language and interactive environment for algorithm development, data visualization, data analysis, and numeric computation.

Matlab (short for matrix laboratory)is a specialized numerical computing environment and programming language.It has built-in support for manipulating matrices, complex numbers, and data visualization.It is widely used by scientists and engineers in industry and academia.Runs on most popular operating systems.Can use as a powerful calculator and data visualization tool. More importantly,you can program in Matlab. Can best exploit and appreciate Matlabafter you've take a course in linear algebra.Here is anonline tutorial.

Features.

Good for rapid prototyping and 'programming in the small.'Many modern programming features tacked on (cell arrays, structures, objects,nested functions, anonymous functions, function pointers, operator overloading),but esoteric and inconsistent notation. As a result manyMatlab programmers never use them.

Availability.

It's proprietary commercial software distributed byThe MathWorks.Many universities have a site license or laboratories whereit is installed.

Hello World.

Matlab is not explicitly compiled.Interactive interpreter: enter commands in Command window (analogous to DrJava Interaction Pane)Save away a sequence of commands in a Script-M file (analogous to sequenceof statements in main()).

Built-in types of data.

'Everything is an array'.Matlab has 15 fundamental types:int8, uint8, int16, uint16, int32, uint32, int64, uint64, single, double,logical, char, cell, structure, and function handle.All of these are in the form of an array (from a minimum of 0-by-0 in sizeto d-dimensional array of any size).Can also access user defined types: user classes and Java classes.The default data type is a 2D array (or matrix) of doubles.Strings = char array (though to create an array of stringsof different sizes, use a cell array).

In Matlab, complex numbers are doubles with a real part andan imaginary part.(Behind the scenes Matlab, stores 2 parallel double vectors,one for the real part and one for the imaginary part.)Good idea to set i = sqrt(-1) before using (since you may havechanged the value of i earlier).

Representation is same as for Java. Floating point numbers use IEEE 754;integers are two's complement.

Scalar operators.+, -, *, / (floating point division), ^ (for exponentiation).

Note: use rem(17, 3) for integer remainder instead of %.

Comparison operators.< <= > >= ~= (instead of !=).Returns a logical, which has the value 1 for trueand 0 for false.

Boolean operators.&&, ||, ~ (instead of !)

Math library.sqrt(), rand(), pi, abs() The followingillustrates how to do basic arithmetic calculations.

Strings.String literal: 'hello' instead of 'hello'.String concatenation: a = ['hello' 'world']

Precedence order.Precedence order, parentheses, associativity.

Statements.Statements end with a semicolon; if you omit the semicolonyou get an echo response.

Variables.Case-sensitive.

Dynamically typed.Java is strongly typed and statically typed.Every expression and variable has a type thatis known (and checked) and compile-time.Matlab is dynamically typed. Variables declared without defining their types.The type is determined at runtime.Seems easier for programmer, but significantly more error-prone.When Matlab encounters a new variable, it automaticallyallocates the right amount of storage; when a variable changes, it re-allocatesmemory if necessary.Weakly typed (type of variable is not enforced, e.g., can concatenatestring '12' and the integer 3 to get '123', then treat it asan integer, all without any explicit conversions).Matlab is very weakly typed.

Disadvantage: errors not discovered until run-time.For example, the constant i is pre-defined as the square root of -1.However, you can redefine it to be an integer or an array.Or, if you name a variable the same name as a function, this willhide the function, making it impossible to call.Be careful!

Conditionals and loops.

Conditionals: if statements are similar to Java.Loops. While loop similar; for loop lessexpressive (can only iterate a variable overthe elements of an array).

Arrays.

Vectors and matrices.

Creating vectors and matrices.(linspace, colon, ones, zeros, rand).

Matrix and vector operations.Indexing: use a(i) to access ith element.Java is 0-based; Matlab is 1-based indexing.Subarray and submatrices using colon notation.

Vector operations: most functions work with vector arguments.Also mean(), min(), max(),std(), median().

Matrix scaling, addition, multiplication, transpose,element-by-element arithmetic.

Vectorization.Prior to Matlab 6.5, very costly to perform loops.JIT-Accelerator improved performance by ordersof magnitude. Must pre-allocate memory before loop.x = linspace(0, 2*pi, N);y = sin(x);vs.x = 0;y = zeros(1, N);for i = 1:N y(i) = sin(2 * pi * (i-1) / N);end

Input and output.

printfprinting System.out.println('Hello') disp('Hello')formatted printing System.out.printf('%8.4fn', x) fprintf('%8.4fn', x)

Functions.

Matlab provides many built-in functions. As in Java, Matlabcannot include ever function that you might need. Accordingly, you can implement your own functions using

M-file functions. Function has same name as the M-file.

Like Java, M-file functions can have any number of input arguments.Unlike Java, they can also have any number of output arguments.

Can return multiple values from a function.(Matlab does have class directories where you putdifferent overloaded functions by putting in separatesubdirectories named @int32 and

Transpose Of Matrix In Matlab

@double

How To Transpose In Matlab

Sound waves. Matlab especially suited to signal processing.

Then, to play a note:

Pass by value.When you call a function (or make an assignment) the argumentsget copied. If you modify the argument within the function,you are modifying a copy of the argument local to the function.To modify variables from wtihin a function you need toreturn the result when finished.

Matlab uses a scheme called copy on write tooptimize when you pass a big array to a function, itonly copies it if you modify one of the variables.Thus, you can freely pass largearrays to functions without worrying about overhead (providedyou don't change them).

But watch out if you pass large arrays and then modifythe variables.Swap function very ineffcient. The following functiontakes time and space proportional to the length of the vector x.Matlab is consistently pass-by-value, so if a function modifies an array,it must return the result via output parameters.

Subfunctions.Can include a helper function in the same M-fileas the primary function. In Matlab, these are calledsubfunctions. They cannot be called directlyfrom outside the M-file, e.g., private.Only the first function defined in a file is public.

Caveat: y = f(x) can be either a function call or an array access,depending on context.

Recursion.

Recursion is fully supported.

- local vs $global$ variables (scope) - $error$, $warning$ - nested functions

Libraries.

A key feature of Matlab is its extensive numerical libraries.Image processing, optimization, ....

Rich libraries for scientific computing: besselj(), gcd(),

Each M-function file can only have onefunction visible to the outside world.Results in a surfeit of files.Matlab programmers can organize a bunch of related M-files intoa toolbox, which basically amounts to storing lotsof files in the same directory.

Linear algebra.

In Matlab, the primary data type is a complex matrix.A scalar is a 1-by-1 matrix; a vector is a 1-by-N or N-by-1 matrix.The following illustrates how to solve systems of linear equationswith the operator. When the system is over-determined, theresult is a least squares solution. (See section xyz.)

One of the most powerful features of Matlab is its extensive numericallinear algebra library.

Matlab Libraries.

Matlab also has numerous libraries geared toward scientific and commercialapplications including: solving systems of ODEs, signal processing, wavelets,equation solving,linear and nonlinear optimization, neural networks, image processing, interpolation,polynomials, data analysis, Fourier transforms, elementary and special mathematicalfunctions, and digital audio.Matlab tutorialAlso string libraries including regular expressions.

Programming in Matlab.Loops, conditionals, functions, building re-usable libraries, function handles,data types (8, 16, 32- bit integers, multi-dimensional arrays, strings, struct).MATLAB includes OOP features, including classes and objects, operator overloading, inheritance, although it is fairly well hidden.It is even possible to call Java from Matlab.However, Matalb does not support passing arguments by reference (pointers).

All objects are immutable - to 'change' an object, you need to pass the object asan input argument and return a new object with the data changed.Private helper methods are implemented by putting the methods in a subdirectorynamed private.Matlab supports operator overloading. use display method as analog of toString().Use subsref to overload subscripted reference, plus, minus,mtimes, for addition, subtraction, and multiplication.

Objects.

Awkward and rarely used in practice.

Function functions. Functions handles are data typesin Matlab.Can pass functions to other functions (feval, eval, fzero, ezplot).

Data structures.

No support for references or pointers.Difficult to implement linked structures.

Integration with Java.

. In Matlab Multiplication

Matlab is tightly integrated with Java - the Matlabinterpreter is written in Java.Can directly call Java code.

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