# Some Basic Operations On Matrices and Vectors.....

The Matlab notation for binary operations on matrices,vectors and there elements are as follows:

•   + : -  For matrix or element addition
•   -  : -  For matrix or element subtraction.
•   .* : - For element wise multiplication
•   *  : - For matrix multiplication
•   ./  : - For element wise division.
•   /   : - For right matrix division (right multiplication by an inverse).
•   \   : - For left matrix division ( left multiplication by an inverse)

There is also Matlab notation for a few unary operations
•   .^  : -  For raising an element to a power.
•   ^   : -  For raising a matrix to a power.
•   '    : -  For converting to complex conjugate transpose (single forward quote).
Matlab also has specific notation and symbols for delimiters, separators, grouping, type assignment, and so forth : Essential among these are :
•  [ ]   : - For vector and Matrix delimiter.
•  ( )   : - For grouping vector and matrix element indicies, function argument delimiter.
•  :      : - For index range separator
•  :      : - For matrix row separator.

• blank space : - For matrix column element separator.
• , comma      : - For matrix index separator, function argument separator.
• . period        : - For radix expansion separator ( American convention).
• ' ' single forward quotes : - For demarcation of character strings..

Hope to see you in next tutorial....!!!!

Written By,
Dheeraj Mor
Student @ VIT University

# LEDs - A Beginners Approach

With Normal single color LED you all might have worked. Its a simple device that generates/emits Light rays, when a positive bias voltage is applied to its terminal. Bi & Tri color LEDs also works on the same principle, as they too are LED.

So Whats Inside an LED (Light Emitting Diode)?

 Light Emitting Diode Internal Structure
As you can see, in the above diagram, there is a very less area that is actually emitting the light, this light is also not coherent, as it contains beam of multiple frequencies (but as a whole they will seem to have a single color). The Light Emitting area where the actual diode is, is covered in specific plastic coating, of a particular shape, which may be float or hemispherical.

 LED Equivalent diagram
As LED are just another diode, (which emits light though), the equivalent circuit diagram can be seen as above. Where positive side is Anode & negative is Anode.

 LED Internal Parts
Above is one more diagram of representing LED's internal Parts...

The LED will Glow iff, you are giving a (+)ive potential to the Anode with respect to Cathode, or simply + pin of battery to Anode & - pin to cathode of LED.

Note: You should not connect LED directly to a 5V or 9V battery ( mentioned as they are commonly available ), because in that case your LED will burn/blown off, & not work further, you should use some resistors to limit the current flowing through it, typically 330 ohms resistors are used as current limiting resistors. You should also not reverse bias the LED, as its threshold is very small, in worst case it might even burst with a bang!
 Different Color Types In LEDs
LEDs are available in market in various colors, single & multi color even, which we are going to discuss in a few moment...

And not only colors are different but you will find that there are even many different types of shapes in which they are available.

 LEDs of Different Shapes
Uses of LEDs are many.....mostly by hobbyist  they are used to create beautiful LED's array..like what in the picture is.
 Colored LED Array
The color of light coming out of the LED coming out of the LED depend on two things:-
** The semiconductor material they are prepared with
** The coating is done over it.
The following picture will show you this...
 LED
So How to get it working in your projects...??
Following photos will show you that how you should connect them, in order to make them work..
 Circuit Diagram True For Every LED
implementing that in breadboard it looks like...
 LED Glowing

If you are not able to grasp, here is one more schematic, that looks like a real world scene..
 LED connection schematic

or if you want to build bigger circuit with much more light...you can try both the below circuits..
 4-LED in parallel
 3-LED in series
There are not only these types of LEDs are available in market, example the different battery status light in your computer systems/laptops do come from LEDs, but they are not of different LEDs, They are generated by a single LED, that is a multicolored LED.

In the next post you will see that how to generate multiple colors with a single multicolored LED, which are capable of generating many color, as per the voltage input provided by experimenter or the user.