How do I calculate logarithm?

We can calculate logarithm using the Math.log10() and the Math.log() static method call.

package org.kodejava.example.math;

public class LogarithmExample {

    public static void main(String[] args) {
        double number1 = 1000.0d;
        double number2 = 999.0d;

        //
        // Get common logarithm
        //
        double log10 = Math.log10(number1);
        System.out.println("Common logarithm of " + number1 + " = " + log10);

        //
        // Get natural logarithm
        //
        double loge = Math.log(number1);
        System.out.println("Natural logarithm of " + number1 + " = " + loge);
    }
}

The output of the program is:

Common logarithm of 1000.0 = 3.0
Natural logarithm of 1000.0 = 6.907755278982137

How do I round a number?

The example below show you some methods of the Math class that can be use to round the value of a number. These methods are Math.ceil(), Math.floor() and Math.round().

package org.kodejava.example.math;

public class GetRoundingValueExample {

    public static void main(String[] args) {
        Double number = 1.5D;

        //
        // Get the smallest value that is greater than or equal to the
        // argument and is equal to a mathematical integer
        //
        double roundUp = Math.ceil(number);
        System.out.println("Result of rounding up of " + number + " = " + roundUp);

        //
        // Get the largest value that is less than or equal to the
        // argument and is equal to a mathematical integer
        //
        double roundDown = Math.floor(number);
        System.out.println("Result of rounding down of " + number + " = " + roundDown);

        //
        // Get the closest long value to the argument
        //
        long round1 = Math.round(number);
        System.out.println("Rounding result of " + number + " (in long) =  " + round1);

        //
        // Get the closest int value to the argument
        //
        int round2 = Math.round(number.floatValue());
        System.out.println("Rounding result of " + number + " (in int) = " + round2);
    }
}

Here are the result of the program:

Result of rounding up of 1.5 = 2.0
Result of rounding down of 1.5 = 1.0
Rounding result of 1.5 (in long) =  2
Rounding result of 1.5 (in int) = 2

How do I calculate cube root and square root of a number?

To calculate the cube root and the square root of a double value we can use the Math.cbrt(double a) and Math.sqrt(double a) static method call.

package org.kodejava.example.math;

public class CubeSquareRootExample {

    public static void main(String[] args) {
        double cube = 125.0d;
        double square = 100.0d;

        // 
        // Get the cube root of double value
        //
        double cbrt = Math.cbrt(cube);
        System.out.println("Cube root of " + cube + " is " + cbrt);

        //
        // Get the square root of double value
        //
        double sqrt = Math.sqrt(square);
        System.out.println("Square root of " + square + " is " + sqrt);
    }

}

This snippet will print the following output:

Cube root of 125.0 is 5.0
Square root of 100.0 is 10.0

How do I use trigonometric calculation methods?

This example demonstrates how to use the trigonometric methods of the Math class. You can see the use of method such as Math.sin(), Math.cos(), Math.tan(), etc.

package org.kodejava.example.math;

public class TrigonometricExample {
    public static void main(String[] args) {
        double radians = 1.0d;

        double sine = Math.sin(radians);
        double cosine = Math.cos(radians);
        double tan = Math.tan(radians);

        double asine = Math.asin(sine);
        double acosine = Math.acos(cosine);
        double atan = Math.atan(tan);

        System.out.println("Sine of " + radians + " = " + sine);
        System.out.println("Cosine of " + radians + " = " + cosine);
        System.out.println("Tangent of " + radians + " = " + tan);
        System.out.println("Arcsine of " + sine + " = " + asine);
        System.out.println("Arccosine of " + cosine + " = " + acosine);
        System.out.println("Arctangent of " + tan + " = " + atan);
    }
}

The output of the program are:

Sine of 1.0 = 0.8414709848078965
Cosine of 1.0 = 0.5403023058681398
Tangent of 1.0 = 1.5574077246549023
Arcsine of 0.8414709848078965 = 1.0
Arccosine of 0.5403023058681398 = 1.0
Arctangent of 1.5574077246549023 = 1.0

How do I convert angle from radians to degrees?

The example below show you how to convert an angle measured in radians into degrees and vice versa. We can use the Math.toDegrees() and Math.toRadians() method call to do the conversion.

package org.kodejava.example.math;

public class RadiansDegreeConversionExample {
    public static void main(String[] args) {
        double radians = 1.0d;
        double degrees = 45d;

        //
        // Converts an angle measured in radians to an
        // approximately equivalent angle measured in
        // degrees.
        //
        double toDegree = Math.toDegrees(radians);

        //
        // Converts an angle measured in degrees to an 
        // approximately equivalent angle measured in 
        // radians.
        //
        double toRadians = Math.toRadians(degrees);

        System.out.println("Radians " + radians + " in degrees = " + toDegree);
        System.out.println("Degrees " + degrees + " in radians = " + toRadians);
    }
}

The result of the snippet above are:

Radians 1.0 in degrees = 57.29577951308232
Degrees 45.0 in radians = 0.7853981633974483