Some Built In Math Methods
Introduction.
We have already made extensive use of the methods showInputDialog( ) and
showMessageDialog( ) as part of the JOptionPane class. There are a
very large variety of built-in methods
in Java. Unfortunately, it can be very difficult to find an
appropriate one when you are looking for it.
Since java.lang is the standard package used to execute java code we will focus on methods that are built into it for this webpage.Hopefully, this little survey will help in this. The Math Class. The following table contains a list of some of the more commonly useful built-in methods to be used for mathematical computations in the class Math. |
class Math in (java.lang package) | ||
Method |
Description |
Example |
Math.abs(x) | Returns the absolute value
of x. Returns a type that matches the type of x. |
Math.abs(-24.5) = 24.5 Math.abs(-2) = 2 |
Math.ceil(x) | Returns the smallest integer
which is not less than x. Returns a type double |
Math.ceil(56.01) = 57.0 |
Math.exp(x) | Returns e^{x }where
e~2.7182818284590455 Returns a type double |
Math.exp(3) = 20.0855369 |
Math.floor(x) | Returns the largest integer
which is less than x. Returns a type double |
Math.floor(56.01) = 56.0 |
Math.log(x) | Returns the natural
logarithm of x Returns a type double |
Math.log(2) = .6931471805 |
Math.max(x,y) | Returns the maximum
of x and y Returns a type that matches the type of x and y |
Math.max(15, 25) = 25 Math.max(45, 25.56) = 45.0 |
Math.min(x,y) | Returns the minimum
of x and y Returns a type that matches the type of x and y |
Math.min(15, 25) = 15 Math.min(45, 25.56) = 25.56 |
Math.pow(x,y) | Returns x^{y }where
x and y are doubles Returns a type double |
Math.pow(2.0, 3.0) = 8.0 Math.pow(4.0, 0.5) = 2.0 |
Math.round(x) | Returns the integer
which is closest to x. Returns a type double |
Math.round(25.51) = 26.0 Math.round(25.4999) = 25.0 |
Math.sqrt(x) | Returns the square root of x
where x is a double. Returns a type double |
Math.round(6.25) = 2.5 Math.round(16.0) = 4.0 |
I am assuming that most of these functions are at least
somewhat familiar to you so I won't work any examples at present.
Though we are likely to make use of some of these in the future. The next couple webpages will cover some built in methods in classes for strings and characters. |