Several factors can be responsible, including: 1  Heredity: If your dad had oily hair, chances are you will, too. 2  Hormonal fluctuations: In adult women, it may come with the menstrual cycle or using birth control pills. 3  Bulking up: Excessive oil is a side effect of using androgenic hormones to increase body mass.
At first glance, a function looks just like a relation. 1  It's a set of ordered pairs such as { (0,1) , (5, 22), (11,9) }. 2  Like a relation, a function has a domain and range made up of the x and y values of ordered pairs.
In mathematics, a function is defined as a relationship between defined values and one or more variables. For example, a simple math function may be: y = 2x. In this example, the relationship of y to x is that y is twice as much as the value assigned to x. While math functions can be far more complex than this, most are simple relative to functions used in computer programming. This may be why math functions are often referred to as expressions, while computer functions are often called procedures or subroutines. Computer functions are similar to math functions in that they may reference parameters, which are passed, or input into the function. If the example above were written as a computer function, x would be the input parameter and y would be the resulting output value. It might look something like this: function double(x) { $y = 2 * x; return $y;}