*calculus is the language of physics. It holds its root everywhere from core classical mechanics to the vast engineering disciplines from signal processing to image processing from the aeronautical design to the building construction . so lets begin our discussion with the very common term function.*

*what is a function , if I want a general laymen explanation than it is the system which takes on a variable and produces another variable which is somehow dependent on the input variable and sometimes not as in the case of a constant function.*

*what mathematics say:->*

*y=f(x) :f(x)=x^2 for xE(R)*

*so it is a mapping of a variable to another variable by a given relation under given condition, the condition that is defined is called domain and set of all the values that are obtained is called range.*

*lets again describe domain and range as in the above case y=f(x) :f(x)=x^2 for all real x;*

*the set of all permissable value on which the function can be defined is called the domain;*

*for example in case of y=(x)^0.5 where x consists of all real values however the function is real only for the positive real numbers including zero so +R is the domain of the given function *

*range from the above case is all possible values that we can achieve from this variable from the very same example the range is [0,infinity) as the minimum value of a function is zero and that of largest is infinty.*

*thank you very much for reading in the next reading we will discuss the types of function.*