__MATLAB__

Basic Features

1)Matlab calls the result as "ans"

For example when you type at the command 4 + 6 and press "enter" the result is displayed as ans = 10.

You can also save the result in a variable let us say x .Just type x = 4 + 6 at the command

and press "enter" the result is displayed as x = 10.

2)Simple Math Operations in Matlab

Operation |
Symbol |
Example |

addition ,a+b |
+ |
3 + 4.2 |

subtraction ,a-b |
- |
4-2.4 |

multiplication ,a |
* |
3*5 |

division ,a / b |
/ |
56/8 |

exponential function ,a power b |
^ |
2^7 |

The evaluation of expressions always take from left to right with the order of precedence being:

a)parenthesis

b)exponential function("^")

c)multiplication (*),division(/)

d)addition (+), subtraction (-)

__Note:__

- Use parenthesis as much possible for better readability and understandability.
- parenthesis are evaluated from innermost parenthesis to the outer most parenthesis.

Matlab Workspace

1)Matlab remembers the commands and variables as they are typed in a workspace called "Matlab Workspace".

2)The command "who" displays all the variables present in the workspace at any instant of time.

3)The cursor arrows can be used at the command prompt to scroll through the commands typed in the particular session.

4)The command "clear" deletes the variables present in the workspace.

Example: Type a =3 ,b=4 at the command prompt.

Type "who" at command prompt (displays the variables present in the session )

Scroll "UP" arrow key of the keyboard (The commands typed earlier are

displayed at the command prompt)

Now Type "a" and press enter(Value of "a" is displayed)

Now Type "clear" (Clears the variables present in the memory)

For a check now type "who" (Nothing is displayed).

Variables

1)Variable names ** **case sensitive.

2)They may contain up to 31 characters.

3)Variables must start with a letter followed by a characters or numbers or under score.

4)Punctuation marks are not allowed in the variable names as they have a special meaning.

5)Apart from the variables matlab has some in built variables ,Some of them are

Special variables |
Description |

pi |
Ratio of circumference to diameter of a circle(22/7) |

i(and) j |
Square Root (-1) |

nargin |
Number of function input arguments used. |

nargout |
Number of function output arguments used. |

__Note__:

- Values stored in a variable is erased when a new value is assigned to it.
- Special variables can be assigned any value but when matlab is restarted or after execution of clear command the original values are restored .

Comments and Punctuation

1)A comment can be written by using a "%" at the beginning of the comment.

Example : a = 4 %This is a comment.

2)Two or more matlab statements can be placed on the same line if they are separated by a comma or a semicolon.

3)A semicolon after a statement suppresses the value to be printed at the command line .

Example : a = 5;(The value of a is not displayed at the command)

4)"Ctrl + C" is pressed to stop the matlab processing .(e.g. Can be used to stop an infinite loop process)

Complex Numbers

1)Assignment of a complex number to a variable "a" can be done in several ways

a = x +yi(e.g. a = 2+6i)

b = x+yi (e.g. a = 2+6j)

c = x +sqrt(-1)*y(e.g. a = 2+sqrt(-1)*6)

2) real(a) Returns the real part of the complex number.

imag(a) Returns the Imaginary part of the complex number.

(e.g. real(2+6i) returns 2 and imag(2+6i) returns 6)

3) let the Polar form of the a+ib be M<x = M.e^jx [x is the angle of gradient and M is the Magnitude].Matlab provides functions to convert from rectangular form to the polar form.

4)abs(a) Returns the magnitude of a [ abs(a) = sqrt(a^2 + b^2)]

5)angle(a) Returns the gradient in radians [angle(a) = atan(b/a)]

e.g. abs(2+6i) = 6.3246 and angle(2+6i) = 1.2490