Page 212 - ComputerScience_Class_11

Example 1: int i = Math.rint(7.8); Output: 8.0
Example 2: int i = Math.rint(7.2); Output: 7.0
Example 3: int i = Math.rint(7.5); Output: 8.0
Example 4: int i = Math.rint(4.5); Output: 4.0
Example 5: int i = Math.rint(9.5); Output: 10.0
[Explanation: In case of 0.5, if it is an even integer value it will return the previous integer value and if it is an odd
integer value it will return the next integer value. See examples 3, 4 and 5.]
For negative fractional numbers:
Example 1: int i = Math.rint(-7.8); Output: -8.0
Example 2: int i = Math.rint(-7.2); Output: -7.0
Example 3: int i = Math.rint(-7.5); Output: -8.0

12. Math.exp()

This function returns the exponential value of the passed argument. It uses a double data type.
Example 1: double d = Math.exp(2.5); Output: 12.182493960703473
13. Math.random()
This function returns a random real number between 0 and 1.
Example 1: Math.random(); Output: 0.001110128

Some special calculations using Math.random()
1. Using this function, we can generate a random number between 1 and x
Say, x=3;

int a = (int)(Math.random() * x) + 1;
[It will return any integer number from 1 to 3]

2. Using this function, we can generate a random number between m and (n -1).
Say, m=2, n=9;
int i = (int)(Math.random() * (n – m));
[It will return any integer number from 2 to 8]
14. Trigonometric Functions

In Java, there are three Trigonometric functions:
• Math.sin()
• Math.cos()
• Math.tan()

In the above methods, the arguments are passed in Radians which are generally derived from degrees. We can
convert degree into radian by using the following formula:

Radian = (π * degree given)/180.0
For example:
If double degree = 60, radian;
radian = (22.0/7.0*60)/180.0 = 1.0476
Example 1: double r = Math.rint(Math.sin(Radian)); Output : 1.0
Example 2: double r = Math.rint(Math.cos(Radian)); Output : 0.0
Example 3: double r = Math.rint(Math.tan(Radian)); Output : 2.0

210 Touchpad Computer Science (Ver. 3.0)-XI