Function
Saturday, February 28, 2009
Weeks ago, while listening in the lectures, Real Analysis lecture, to be more specific, the lecturer taught us this --> Function.
Students in science stream will be exposed to function when they're in Form 4. Well, this should be the first topic of the add maths if I'm not mistaken. ^^
So, function. The definition of function is...
Let A and B be sets. f is said to be a function from set A to set B if and only if for each element x of A there is associated a uniquely determined element f(x) of B. The set A is called the domain of f and the elements f(x) are called the values of f. The set of all values of f is called the range of f.
Notation: f : A --> B and read as f is a function from A to B
-From Real Analysis's lecture notes-
Which means that, a function can be called a function when the f : A --> B are injective (one-one), subjective (onto) or bijective (both injective and subjective). In a simple form, function is a many-to-one and one-to-one relation. A one-to-many relation is not a function.
Some may think is hard to remember. But no worries. Thanks to my friend who came out with an idea on how to memorise it.
Let A (domain) as MEN, and B (range) as WOMEN 
Men cannot live without women, but women can live without men. (This is one-one relation. So, it's a function.)
Two men can have the same woman on the same time...(This is many-to-one relation. So, is a function too!)
.. but one man cannot have more than one woman at the same time.(This is not a function cos is a one-to-many relation)
So, can u remember what relation should the function be in order to call a function? ^^
Posts
Wednesday, March 04, 2009 5:05:00 AM
I never thought of this! ugh, i just finished my math course.. wish i knew bout this earlier.. this is much easier to remember.. haha
Wednesday, March 04, 2009 2:38:00 PM
yea.. actually it is much more easier to remember.. ^^