CS 115 OBJECT ORIENTED PROGRAMMING I LECTURE 4

CS 115 OBJECT ORIENTED PROGRAMMING I LECTURE 4 part 3 GEORGE KOUTSOGIANNAKIS

Topic • Math Library Class.

About the Math Library class • The Math class provides static constants and static methods for performing common calculations. • The Math class is in the java. lang package, so it does not need to be imported • The methods of this class are all static. – A static method is a method that can be invoked (called) by using the name of the class that it belongs and the. Operator – For example to call the method random ( a method that produces random numbers) we use Math. random(); 3

Math Library class • Checking the API documentation for random we see the description: public static double random() Returns a double value with a positive sign, greater than or equal to 0. 0 and less than 1. 0. Returned values are chosen pseudorandomly with (approximately) uniform distribution from that range. 4

Math Library class Two static constants PI - the value of pi E - the base of the natural logarithm Example: System. out. println( Math. PI ); System. out. println( Math. E ); The output is: 3. 141592653589793 2. 71828459045 5

Sample Methods of the Math Class Return type data. Type. Of. Arg double Method name and argument list abs( data. Type arg ) returns the absolute value of the argument arg, which can be a double, float, int or long. log( double a ) double returns the natural logarithm (in base e) of its argument. sqrt( double a ) returns the positive square root of a pow( double base, double exp ) double returns the value of base raised to the power exp

The Math min/max Methods Return type Method name and argument list data. Type. Of. Args min( data. Type a, data. Type b ) returns the smaller of the two arguments. The arguments can be doubles, floats, ints, or longs. data. Type. Of. Args max( data. Type a, data. Type b ) returns the larger of the two arguments. The arguments can be doubles, floats, ints, or longs. Find smallest of three numbers: int smaller = Math. min( num 1, num 2 ); int smallest = Math. min( smaller, num 3 ); See Example 3. 16 in Text -Math. Min. Max. Methods. java

Another Example program using the Math Class import java. util. Scanner; public class My. Math. Class { public static void main(String[] args) { double exponent=4. 0; double result=0. 00; double sqrt=0. 00; result=Math. pow(10, exponent); sqrt=Math. sqrt(exponent); System. out. println("The result is"+“ "+result); System. out. println("The square root of the number”+” “++exponent+” ”+” is"+” “+sqrt); } } 8