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Java - Math.floorMod() Examples

Java Java API 

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Class:

java.lang.Math

java.lang.Objectjava.lang.Objectjava.lang.Mathjava.lang.MathLogicBig

Methods:

public static int floorMod(int x,
                           int y)

Returns the floor modulus of the int arguments.

The floor modulus is x - (floorDiv(x, y) * y) , has the same sign as the divisor y , and is in the range of
-abs(y) < r < +abs(y) .

The relationship between floorDiv and floorMod is such that:

  • floorDiv(x, y) * y + floorMod(x, y) == x

The difference in values between floorMod and the % operator is due to the difference between floorDiv that returns the integer less than or equal to the quotient and the / operator that returns the integer closest to zero.

If the signs of arguments are unknown and a positive modulus is needed it can be computed as (floorMod(x, y) + abs(y)) % abs(y).

Parameters:
x - the dividend
y - the divisor
Returns:
the floor modulus x - (floorDiv(x, y) * y)
Throws:
java.lang.ArithmeticException,ArithmeticException - if the divisor y is zero
Since:
1.8



public static int floorMod(long x,
                           int y)

Returns the floor modulus of the long and int arguments.

The floor modulus is x - (floorDiv(x, y) * y) , has the same sign as the divisor y , and is in the range of -abs(y) < r < +abs(y) .

The relationship between floorDiv and floorMod is such that:

  • floorDiv(x, y) * y + floorMod(x, y) == x
Parameters:
x - the dividend
y - the divisor
Returns:
the floor modulus x - (floorDiv(x, y) * y)
Throws:
java.lang.ArithmeticException,ArithmeticException - if the divisor y is zero
Since:
9



public static long floorMod(long x,
                            long y)

Returns the floor modulus of the long arguments.

The floor modulus is x - (floorDiv(x, y) * y) , has the same sign as the divisor y , and is in the range of -abs(y) < r < +abs(y) .

The relationship between floorDiv and floorMod is such that:

  • floorDiv(x, y) * y + floorMod(x, y) == x
Parameters:
x - the dividend
y - the divisor
Returns:
the floor modulus x - (floorDiv(x, y) * y)
Throws:
java.lang.ArithmeticException,ArithmeticException - if the divisor y is zero
Since:
1.8


Examples


package com.logicbig.example.math;

public class FloorModExample {

    public static void main(String... args) {
        findFloorMod(61, 5);
        findFloorMod(61, -5);
        findFloorMod(-25, Integer.MIN_VALUE);
        findFloorMod(250, 0);
        findFloorMod(Integer.MAX_VALUE, -4);
    }

    public static void findFloorMod(int x, int y) {
        System.out.println("-----------");
        try {
            System.out.printf("%s %% %s = %s%n", x, y, x % y);
            System.out.printf("Math.floorMod(%s, %s) = %s%n", x, y, Math.floorMod(x, y));
        } catch (ArithmeticException e) {
            System.out.println("error: " + e);
        }
    }
}

Output

-----------
61 % 5 = 1
Math.floorMod(61, 5) = 1
-----------
61 % -5 = 1
Math.floorMod(61, -5) = -4
-----------
-25 % -2147483648 = -25
Math.floorMod(-25, -2147483648) = -25
-----------
error: java.lang.ArithmeticException: / by zero
-----------
2147483647 % -4 = 3
Math.floorMod(2147483647, -4) = -1




package com.logicbig.example.math;

public class FloorModExample2 {

    public static void main(String... args) {
        findFloorMod(35, -2);
        findFloorMod(Long.MIN_VALUE, -4);
        findFloorMod(-15, 3);
        findFloorMod(120, 0);
        findFloorMod(Long.MAX_VALUE, -5);
    }

    public static void findFloorMod(long x, long y) {
        System.out.println("-----------");
        try {
            System.out.printf("%s %% %s = %s%n", x, y, x % y);
            System.out.printf("Math.floorMod(%s, %s) = %s%n", x, y, Math.floorMod(x, y));
        } catch (ArithmeticException e) {
            System.out.println("error: " + e);
        }
    }

}

Output

-----------
35 % -2 = 1
Math.floorMod(35, -2) = -1
-----------
-9223372036854775808 % -4 = 0
Math.floorMod(-9223372036854775808, -4) = 0
-----------
-15 % 3 = 0
Math.floorMod(-15, 3) = 0
-----------
error: java.lang.ArithmeticException: / by zero
-----------
9223372036854775807 % -5 = 2
Math.floorMod(9223372036854775807, -5) = -3




package com.logicbig.example.math;

public class FloorModExample3 {

    public static void main(String... args) {
        System.out.println("Prove that floorDiv(x, y) * y + floorMod(x, y) == x");
        values(23, 3);
        values(31, -15);
        values(-15, Long.MIN_VALUE);
        values(300, 0);
        values(Long.MAX_VALUE, -4);
    }

    public static void values(long x, long y) {

        try {
            System.out.println("-----------");
            long floorDivision = Math.floorDiv(x, y);
            long floorModulus = Math.floorMod(x, y);
            System.out.printf("floorDiv(%s,%s) x %s + floorMod(%s,%s) == %s%n", x, y, y, x, y, x);
            System.out.printf("==> %s == %s%n", floorDivision * y + floorModulus, x);
        } catch (ArithmeticException e) {
            System.out.println("error: " + e);
        }

    }
}

Output

Prove that floorDiv(x, y) * y + floorMod(x, y) == x
-----------
floorDiv(23,3) x 3 + floorMod(23,3) == 23
==> 23 == 23
-----------
floorDiv(31,-15) x -15 + floorMod(31,-15) == 31
==> 31 == 31
-----------
floorDiv(-15,-9223372036854775808) x -9223372036854775808 + floorMod(-15,-9223372036854775808) == -15
==> -15 == -15
-----------
error: java.lang.ArithmeticException: / by zero
-----------
floorDiv(9223372036854775807,-4) x -4 + floorMod(9223372036854775807,-4) == 9223372036854775807
==> 9223372036854775807 == 9223372036854775807

See Also