>> MATLAB is just like a supper fast calculator. You can enter commands at the ( >> ) command prompt. MATLAB can solve it immediately.
>> Type a valid expression in MATLAB, for example,
5 + 5
in command window and press ENTER it immediately returns the result
ans = 10
It store the answer in default variable name ans.
Let us look few more examples:
1. 2 ^ 3 ( 2 raised to the power of 3 )
ans = 8
2. sin (pi / 2) ( sine of angle 90 )
ans = 1
3. 7/0 ( Divide by zero )
ans = Inf
4. 732 * 20.3
ans = 1.4860 e + 04
>> MATLAB provides some special expressions for some mathematical symbols, like pi for π, Inf for ∞, (i and j) for √-1 etc. Nan stands for 'not a number'.
>> MATLAB retains your previous keystrokes. Use the up-arrow key to scroll back through the commands. Press the key once to see the previous entry, and so on. Edit a line using the left- and right-arrow keys the Backspace key, and the Delete key.
>>Press the Enter key to execute the command.
Use of Semicolon (;) in MATLAB:
Semicolon (;) indicates end of statement. However, if you want to suppress and hide the MATLAB output for an expression, add a semicolon after the expression. For example,
x = 3;
y = x + 5
When you click the Execute button, MATLAB executes it immediately and the result returned is:
y = 8
It not show x = 3.Comments in MATLAB:
In MATLAB we use percent symbol ( % ) for comments. For example,
x = 9 % assign the value 9 to x
You can also write a block of comments using the block comment operators % { and % }. It start with % { and end with % }. The MATLAB editor includes tools and context menu items to help you add, remove, or change the format of comments.
Arithmetic Operations
Addition operator
|
|
-
|
|
*
|
|
.*
|
Array multiplication operator.
|
^
|
Scalar and matrix exponentiation operator.
|
.^
|
Array exponentiation operator.
|
\
|
Left-division operator.
|
/
|
Right-division operator.
|
.\
|
Array left-division operator.
|
./
|
Array right-division operator.
|
:
|
Generates regularly spaced elements and represents an entire row or column.
|
( )
|
Encloses function arguments and array indices; overrides precedence.
|
[ ]
|
Enclosures array elements
|
.
|
Decimal point.
|
...
|
Ellipsis. Line-continuation operator
|
,
|
Separates statements and elements in a row
|
;
|
Separates columns and suppresses display.
|
%
|
Designates a comment and specifies formatting.
|
_
|
|
._
|
Non conjugated transpose operator.
|
=
|
Assignment operator.
|
Order of Precedence:
First : Parentheses, evaluated starting with the innermost pair.
Second : Exponentiation, evaluated from left to right.
Third : Multiplication and division with equal precedence, evaluated from left to right.
Fourth : Addition and subtraction with equal precedence, evaluated from left to right.
Examples of Precedence:
Try it yourself in MATLAB
The Assignment Operator ( = ) :
Typing x = 3 assigns the value 3 to the variable x. We can then type x = x + 2. This assigns the value 3 + 2 = 5 to x. In algebra we can write x + 2 = 20, but in MATLAB we cannot. In MATLAB the left side of the = operator must be a single variable. The right side must be a computable value
Commands for managing the work session:
Special Variables and Constants:
Naming Variables:
Variable names consist of a letter followed by any number of letters, digits or underscore. MATLAB is case-sensitive. Variable names can be of any length, however, MATLAB uses only first N characters, where N is given by the function namelengthmax.
Complex Number Operations:
>> The number c1 = 1 – 2i is entered as follows:
>> An asterisk is not needed between i or j and a number, although it is required with a variable, such as
>> Be careful. The expressions y = 7 / 2 * i and x = 7 / 2 i give two different results:
Numeric Display Formats:
Some Commonly Used Mathematical Functions:
Note: The MATLAB trigonometric functions use radian measure.
Saving your work:
The save command is used for saving all the variables in the workspace, as a file with .mat extension, in the current directory. For example,
>> save myfile
You can reload the file anytime later using the load command.
>> load myfile
clc
|
Clears the Command window.
|
clear
|
Removes all variables from memory.
|
clear v1 v2
|
Removes the variables v1 and v2
from memory.
|
exist ( ' var ' )
|
Determines if a file or variable
exists having the name ‘var’.
|
quit
|
Stops MATLAB.
|
who
|
Lists the variables currently in
memory.
|
whos
|
Lists the current variables and
sizes, and indicates if they have imaginary parts.
|
exit
|
Exit MATLAB
|
:
|
Colon; generates an array having
regularly spaced elements.
|
Special Variables and Constants:
ans
|
|
i , j
|
i , j The imaginary unit √-1.
|
Inf
|
|
NaN
|
Not a number. Indicates an undefined numerical result.
|
pi
|
The number π.
|
eps
|
Accuracy of floating-point precision.
|
exp
|
Stand for exponential
|
Naming Variables:
Variable names consist of a letter followed by any number of letters, digits or underscore. MATLAB is case-sensitive. Variable names can be of any length, however, MATLAB uses only first N characters, where N is given by the function namelengthmax.
Complex Number Operations:
>> The number c1 = 1 – 2i is entered as follows:
c1 = 1 - 2i
>> An asterisk is not needed between i or j and a number, although it is required with a variable, such as
c2 = 5 - i*c1
y = ( 7 / 2 ) i = 3.5i and x = 7 / (2 i) = –3.5i.
Numeric Display Formats:
format rat
|
Gives the answer in rational form e.g.
format rat
x=0.5
This gives 1 / 2
|
format short
|
Four decimal digits (the default); 13.6745.
|
format long
|
|
format short e
|
Five digits (four decimals) plus exponent; 6.3792 e + 03.
|
format long e
|
16 digits (15 decimals) plus exponent; 6.379243784781294 e – 04.
|
Some Commonly Used Mathematical Functions:
Note: The MATLAB trigonometric functions use radian measure.
Saving your work:
The save command is used for saving all the variables in the workspace, as a file with .mat extension, in the current directory. For example,
>> save myfile
You can reload the file anytime later using the load command.
>> load myfile
0Awesome Comments!