BigFraction

Java library that represents a fraction as a ratio of two BigIntegers, reduced to lowest terms. A rich set of mathematical functions are supported.

Creating BigFractions

Constructors are protected. Create new BigFractions using valueOf(Number numerator), valueOf(Number numerator, Number denominator), or valueOf(String):

BigFraction.valueOf(11);      // 11/1
BigFraction.valueOf(11, 17);  // 11/17
BigFraction.valueOf("19/81"); // 19/81

Fractions are always reduced to lowest terms:

BigFraction.valueOf(17, 34);  // 1/2
BigFraction.valueOf(0, 999);  // 0/1

The sign is always carried by the numerator:

BigFraction.valueOf(-9, 4);   // -9/4
BigFraction.valueOf(9, -4);   // -9/4
BigFraction.valueOf(-9, -4);  // 9/4  (negatives cancel out)

You can use floating point numbers to create the fraction:

BigFraction.valueOf(0.625);  // 5/8
BigFraction.valueOf(-8.5, 6.25); //-34/25

But be careful, what you get is exactly equal to the value you provide:

BigFraction.valueOf(1.1);  // 2476979795053773/2251799813685248
BigFraction.valueOf(1.1f); // 9227469/8388608

The version that takes a String may be more like what you expect:

BigFraction.valueOf("1.1");                // 11/10
BigFraction.valueOf(Double.toString(1.1)); // 11/10
BigFraction.valueOf(Float.toString(1.1f)); // 11/10

You can also use BigInteger and BigDecimal:

BigFraction.valueOf(new BigInteger("9999999999999999999"), BigInteger.valueOf(1));
// ->  9999999999999999999/1   (note that this is larger than Long.MAX_VALUE)

BigFraction.valueOf(new BigDecimal("1.23456789012345678901E-50"));
// ->  123456789012345678901/10000000000000000000000000000000000000000000000000000000000000000000000

You can even mix different Number types for numerator and denominator:

BigFraction.valueOf(1.5, BigInteger.valueOf(17)); // 3/34

A few exceptions:

BigFraction.valueOf(1,0); // ArithmeticException - divide by zero
BigFraction.valueOf(0,0); // ArithmeticException - divide by zero
BigFraction.valueOf(Double.POSITIVE_INFINITY); //IllegalArgumentException
BigFraction.valueOf(Double.NaN); //IllegalArgumentException

Mathematical Operations

BigFraction a = BigFraction.valueOf(1,2);
BigFraction b = BigFraction.valueOf(3,4);
BigFraction z = BigFraction.ZERO;

a.add(a); // 1/2 + 1/2 = 1/1
a.add(b); // 1/2 + 3/4 = 5/4
b.add(z); // 3/4 + 0/1 = 3/4
z.add(a); // 0/1 + 1/2 = 1/2

a.subtract(a); // 1/2 - 1/2 = 0/1
a.subtract(b); // 1/2 - 3/4 = -1/4
b.subtract(z); // 3/4 - 0/1 = 3/4
z.subtract(a); // 0/1 - 1/2 = -1/2

a.multiply(a); // (1/2) * (1/2) = 1/4
a.multiply(b); // (1/2) * (3/4) = 3/8
b.multiply(z); // (3/4) * (0/1) = 0/1
z.multiply(a); // (0/1) * (1/2) = 0/1

a.divide(a); // (1/2) / (1/2) = 1/1
a.divide(b); // (1/2) / (3/4) = 2/3
b.divide(z); // => ArithmeticException - divide by zero
z.divide(a); // (0/1) / (1/2) = 0/1

a.pow(3);  // (1/2)^3 = 1/8
b.pow(4);  // (3/4)^4 = 81/256
a.pow(0);  // (1/2)^0 = 1/1
z.pow(0);  // (0/1)^0 = 1/1  => Mathematicians may not like it, but this is consistent with Math.pow()

a.pow(-3); // (1/2)^(-3) = 8/1
b.pow(-4); // (3/4)^(-4) = 256/81
z.pow(-1); // => ArithmeticException (divide by zero)

a.reciprocal(); // (1/2)^(-1) = 2/1
b.reciprocal(); // (3/4)^(-1) = 4/3
z.reciprocal(); // => ArithmeticException (divide by zero)

Complement is 1 - n. Useful in statistics a lot:

a.complement(); // 1 - 1/2 = 1/2
b.complement(); // 1 - 3/4 = 1/4
z.complement(); // 1 - 0/1 = 1/1

LongFraction

There is also a LongFraction that represents a fraction as a ratio of two longs, with the same methods as BigFraction. The mathematics are much faster, but you run the risk of overflows.

How to Get BigFraction

The library is available via Maven Central and can be used in any project built using Maven or a compatible build tool (Ivy, Gradle, etc.).

You can also download the jar file from the repository and manually add it to your project, if you are not utilizing a supported build tool.

Support for Older Java Versions

I am currently building my jar files using Java 8, with source compatibility only for Java 8+. These jar files will not run in older versions of Java. If you need support for Java 6 or Java 7, notice that there are -java6 or -java7 versions available from Maven. These are compiled with compatibility to that Java version.