Examples of java.lang.Math Methods
Here is an example program that exercises most of the routines in java.lang.Math. If your high school math is a little rusty, don't worry if you don't remember the exact meaning of logarithms or cosines. Just know that they're here in Java if you need them.
public class MathLibraryExample {
public static void main(String[] args) {
int i = 7;
int j = -9;
double x = 72.3;
double y = 0.34;
System.out.println("i is " + i);
System.out.println("j is " + j);
System.out.println("x is " + x);
System.out.println("y is " + y);
// The absolute value of a number is equal to
// the number if the number is positive or
// zero and equal to the negative of the number
// if the number is negative.
System.out.println("|" + i + "| is " + Math.abs(i));
System.out.println("|" + j + "| is " + Math.abs(j));
System.out.println("|" + x + "| is " + Math.abs(x));
System.out.println("|" + y + "| is " + Math.abs(y));
// Truncating and Rounding functions
// You can round off a floating point number
// to the nearest integer with round()
System.out.println(x + " is approximately " + Math.round(x));
System.out.println(y + " is approximately " + Math.round(y));
// The "ceiling" of a number is the
// smallest integer greater than or equal to
// the number. Every integer is its own
// ceiling.
System.out.println("The ceiling of " + i + " is " + Math.ceil(i));
System.out.println("The ceiling of " + j + " is " + Math.ceil(j));
System.out.println("The ceiling of " + x + " is " + Math.ceil(x));
System.out.println("The ceiling of " + y + " is " + Math.ceil(y));
// The "floor" of a number is the largest
// integer less than or equal to the number.
// Every integer is its own floor.
System.out.println("The floor of " + i + " is " + Math.floor(i));
System.out.println("The floor of " + j + " is " + Math.floor(j));
System.out.println("The floor of " + x + " is " + Math.floor(x));
System.out.println("The floor of " + y + " is " + Math.floor(y));
// Comparison operators
// min() returns the smaller of the two arguments you pass it
System.out.println("min(" + i + "," + j + ") is " + Math.min(i,j));
System.out.println("min(" + x + "," + y + ") is " + Math.min(x,y));
System.out.println("min(" + i + "," + x + ") is " + Math.min(i,x));
System.out.println("min(" + y + "," + j + ") is " + Math.min(y,j));
// There's a corresponding max() method
// that returns the larger of two numbers
System.out.println("max(" + i + "," + j + ") is " + Math.max(i,j));
System.out.println("max(" + x + "," + y + ") is " + Math.max(x,y));
System.out.println("max(" + i + "," + x + ") is " + Math.max(i,x));
System.out.println("max(" + y + "," + j + ") is " + Math.max(y,j));
// The Math library defines a couple
// of useful constants:
System.out.println("Pi is " + Math.PI);
System.out.println("e is " + Math.E);
// Trigonometric methods
// All arguments are given in radians
// Convert a 45 degree angle to radians
double angle = 45.0 * 2.0 * Math.PI/360.0;
System.out.println("cos(" + angle + ") is " + Math.cos(angle));
System.out.println("sin(" + angle + ") is " + Math.sin(angle));
// Inverse Trigonometric methods
// All values are returned as radians
double value = 0.707;
System.out.println("acos(" + value + ") is " + Math.acos(value));
System.out.println("asin(" + value + ") is " + Math.asin(value));
System.out.println("atan(" + value + ") is " + Math.atan(value));
// Exponential and Logarithmic Methods
// exp(a) returns e (2.71828...) raised
// to the power of a.
System.out.println("exp(1.0) is " + Math.exp(1.0));
System.out.println("exp(10.0) is " + Math.exp(10.0));
System.out.println("exp(0.0) is " + Math.exp(0.0));
// log(a) returns the natural
// logarithm (base e) of a.
System.out.println("log(1.0) is " + Math.log(1.0));
System.out.println("log(10.0) is " + Math.log(10.0));
System.out.println("log(Math.E) is " + Math.log(Math.E));
// pow(x, y) returns the x raised
// to the yth power.
System.out.println("pow(2.0, 2.0) is " + Math.pow(2.0,2.0));
System.out.println("pow(10.0, 3.5) is " + Math.pow(10.0,3.5));
System.out.println("pow(8, -1) is " + Math.pow(8,-1));
// sqrt(x) returns the square root of x.
for (i=0; i < 10; i++) {
System.out.println(
"The square root of " + i + " is " + Math.sqrt(i));
}
// Finally there's one Random method
// that returns a pseudo-random number
// between 0.0 and 1.0;
System.out.println("Here's one random number: " + Math.random());
System.out.println("Here's another random number: " + Math.random());
}
}
Here's the output from the math library example
i is 7 j is -9 x is 72.3 y is 0.34 |7| is 7 |-9| is 9 |72.3| is 72.3 |0.34| is 0.34 72.3 is approximately 72 0.34 is approximately 0 The ceiling of 7 is 7 The ceiling of -9 is -9 The ceiling of 72.3 is 73 The ceiling of 0.34 is 1 The floor of 7 is 7 The floor of -9 is -9 The floor of 72.3 is 72 The floor of 0.34 is 0 min(7,-9) is -9 min(72.3,0.34) is 0.34 min(7,72.3) is 7 min(0.34,-9) is -9 max(7,-9) is 7 max(72.3,0.34) is 72.3 max(7,72.3) is 72.3 max(0.34,-9) is 0.34 Pi is 3.14159 e is 2.71828 cos(0.785398) is 0.707107 sin(0.785398) is 0.707107 acos(0.707) is 0.785549 asin(0.707) is 0.785247 atan(0.707) is 0.615409 exp(1.0) is 2.71828 exp(10.0) is 22026.5 exp(0.0) is 1 log(1.0) is 0 log(10.0) is 2.30259 log(Math.E) is 1 pow(2.0, 2.0) is 4 pow(10.0, 3.5) is 3162.28 pow(8, -1) is 0.125 The square root of 0 is 0 The square root of 1 is 1 The square root of 2 is 1.41421 The square root of 3 is 1.73205 The square root of 4 is 2 The square root of 5 is 2.23607 The square root of 6 is 2.44949 The square root of 7 is 2.64575 The square root of 8 is 2.82843 The square root of 9 is 3 Here's one random number: 0.820582 Here's another random number: 0.866157
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