Setting DTD standards for HTML/XML documents

DOCTYPE tag is used to include the dtd definition file for a xml or html file. 

DOCTYPE element is placed in the top of the xml/html files.

If it is xml file DOCTYPE tag can be placed right below as a second statement in the file. We have to keep this in mind, this tag (<?xml version-"1.0" encoding="utf-8"?>) is optional in the xml document.

If it is html file DOCTYPE tag can be placed at the top of the html file as a first statement.

DOCTYPE syntax

<!DOCTYPE
root_element_name
PUBLIC||SYSTEM
"[Registration]// [Organization]// [Type] [Label]// [Language]"
"dtd_file_link">

Exameple:-
<!DOCTYPE application PUBLIC '-//Sun Microsystems, Inc.//DTD J2EE Application 1.3//EN' 'http://java.sun.com/dtd/application_1_3.dtd'>

root_element_name - root node name of html/xml

PUBLIC||SYSTEM - PUBLIC is used if "dtd link" available in public over the net, so we can use http link. SYSTEM is used if "dtd link" available in local source that can be addressed via file:/// link.

Quotes can be double quote or single quote and shouldn't be mixed one

"[Registration]// [Organization]// [Type] [Label]// [Language]"
[Registration] - Indicated by either a plus ("+") or minus ("-"). A plus symbol indicates that the organization name that follows is ISO-registered. A minus sign indicates the organization name is not registered. The IETF and W3C are not registered ISO organizations and thus use a "-".
[Organization] - This is the "OwnerID" - a unique label indicating the name of the entity or organization responsible for the creation and/or maintenance of the artifact (DTD, etc.) being referenced by the DOCTYPE. The IETF and W3C are the two originating organizations of the official HTML/XHTML DTDs.
[Type] - This is the "Public Text Class" - the type of object being referenced. There are many different keywords possible here, but in the case of an HTML/XHTML DTD, it is "DTD" - a Document Type Definition.
[Label] - This is the "Public Text Description" - a unique descriptive name for the public text (DTD) being referenced. If the public text changes for any reason, a new Public Text Description string should be created for it.
[Language] - This is the "Public Text Language"; the natural language encoding system used in the creation of the referenced object. It is written as an ISO 639 language code (uppercase, two letters.) HTML/XHTML DTDs are usually (always?) written in English ("EN".)

dtd_file_link - link of the dtd file written. It is optional. Without this xml/html document follows normal standards given by w3c.

What is Logarithm? Logarithm table is very useful while doing scientific calculation

What is Logarithm?

Logarithm is the way by which complex multiplication and division can be accompanied with Logarithm table. It basically used for scientific calculations (Division and Multiplication). It works for the decimal number system.

Example

(2.3008*10²) *(4.3004*10³) =2.3008*4.3004*10⁵

2.3008*10³/4.30004*10²=2.3008*10/4.30004

Rather multiplying rational numbers as shown above, we can take log values of the number and add them in case of multiplication and subtract from one another in case of division. Finally fetch out the corresponding anti-log value, so you can get the result of the calculation.

HOW DOES IT WORK?

In general, it works on a simple logic. When the values are same and the values has some power value, then this is applied - In order to multiply two numbers (which has the same value but has some power value, then) we just need to add the power value. And in case of division it has to be subtracted by the denominator power value.

10²*10³ =10⁵

10³/10²=10¹ …. = 10

In order to make Logarithm table the power values of the base 10’s are tabulated for the whole number and corrections also tabulated for the rational value of the number. Let’s say I need to see the Log value of 2. Then the value obeys this,

Log 2= 0.3010

And 10^0.3010=2 (Approximately)

i.e., Anti-Log 0.3010 = 2

So the log values can be summed when the actual values needs to be multiplied. And in case of division, subtraction can be applied.

To define it simply

a=10^{log a}=Anti-Log(log a)

NOW let’s take up one Multiplication scenario

a*b

a=10^{log a}; b=10^{log b};

Therefore a*b is equals to 10^{log a} X 10^{log b}, hence

a*b = 10^{log a + log b}

And it is nothing but Anti-Log (log a + log b).

Lets write like this a*b = Anti-Log (log a + log b).

In the same way a/b = Anti-Log (log a - log b).

As said earlier in this article, generally logarithm is used for scientific calculations, it is known that scientific values are represented as follows,

x.xxxx * 10 ^{+/- xxx}

And it is obvious we just need to sum or subtract the power value of 10, and by using Log tables we can perform multiplication or division for the number. So we can just ignore the sections 10 ^{+/- xxx}of the scientific notation, because it is known that calculating this section as part of the arithmetic operation is easier.

If you look the logarithm table Log values are available for the range 1 to 99 and its rational values. And Anti-Log values also available only to comply that range.

What is Physics and Chemistry?

Physics vs Chemistry

1) what is Chemistry?

With respect to physics, understanding it in very abstract level upto what the state and it's reaction can be captured in proper metrics, which helps to understand kind of reaction in all physical existence. Applicability of physical properties/principles of the reaction could be much complicated, may not measured at all, sometimes, but its implied logic is very formal across; under a given well defined physical circumstance.

2) what is Physics?

Physics is the way of understanding the "natural existence of phenomena" and it's properties/principles, and also understanding its applicability (in a measurable way).

NOTE: In physics, type and size are highly matters. When it changes the applicable/applied formula also changes, doesn't matter how tiny or how big it is.

Physical Constants

There are lot of physical constants which we use in physics in general for calculation. Even those are depend on size, means phenomenal size and the basic formation and the whole size. For example earth is almost a sphere and its constitute of Atoms that is the phenomena. The gravity g is derived by using both in consideration. And it is constant because of the nature of mathematics. Refer the knols.

1) http://knol.google.com/k/anand-sadasivam/three-random-points-triangle-circle/14aqr8lbuwpu8/12#
2) http://knol.google.com/k/anand-sadasivam/four-random-points-sphere/14aqr8lbuwpu8/13#

The above two knols are incomplete for now however it is understandable that there are lot constants can derived out of it. Particularly in a sphere, perfect two same size cones, one reverse to the other can be kept. The plane inter section gives to that cones will yield so many basic constructs - parabola, hyperbola, ellipse, circle. That can yield many constants based on their nature. And also it can be fit in a cylinder. Refer the page in which it is documented

http://en.wikipedia.org/wiki/Conic_section