Rational Numbers

Instructions

A rational number is defined as the quotient of two integers a and b, called the numerator and denominator, respectively, where b != 0.

The absolute value |r| of the rational number r = a/b is equal to |a|/|b|.

The sum of two rational numbers r₁ = a₁/b₁ and r₂ = a₂/b₂ is r₁ + r₂ = a₁/b₁ + a₂/b₂ = (a₁ * b₂ + a₂ * b₁) / (b₁ * b₂).

The difference of two rational numbers r₁ = a₁/b₁ and r₂ = a₂/b₂ is r₁ - r₂ = a₁/b₁ - a₂/b₂ = (a₁ * b₂ - a₂ * b₁) / (b₁ * b₂).

The product (multiplication) of two rational numbers r₁ = a₁/b₁ and r₂ = a₂/b₂ is r₁ * r₂ = (a₁ * a₂) / (b₁ * b₂).

Dividing a rational number r₁ = a₁/b₁ by another r₂ = a₂/b₂ is r₁ / r₂ = (a₁ * b₂) / (a₂ * b₁) if a₂ is not zero.

Exponentiation of a rational number r = a/b to a non-negative integer power n is r^n = (a^n)/(b^n).

Exponentiation of a rational number r = a/b to a negative integer power n is r^n = (b^m)/(a^m), where m = |n|.

Exponentiation of a rational number r = a/b to a real (floating-point) number x is the quotient (a^x)/(b^x), which is a real number.

Exponentiation of a real number x to a rational number r = a/b is x^(a/b) = root(x^a, b), where root(p, q) is the qth root of p.

Implement the following operations:

• conversion and promotion of integers to rationals. Read the manual's chaper on conversion and promotion for details about how and why to do this.
• addition, subtraction, multiplication and division of two rational numbers
• absolute value, exponentiation of a given rational number to an integer power, exponentiation of a real number to a rational number
• comparison (less than, equals, etc.) of two rational numbers, comparison of a rational number and an integer

In Julia, there are fallback methods already defined for many arithmetic methods, comparisons, etc, especially for subtypes of Real. You do not need to write your own method for >= if you have already defined <; nor do you need to define ^(::RationalNumber, ::Integer) if you have provided a method for multiplication; etc. You can examine the fallback methods for a given function by entering methods(abs) or edit(abs, (RationalNumber, RationalNumber)) at the REPL.

Your implementation of rational numbers should always be reduced to lowest terms. For example, 4/4 should reduce to 1/1, 30/60 should reduce to 1/2, 12/8 should reduce to 3/2, etc. To reduce a rational number r = a/b, divide a and b by the greatest common divisor (gcd) of a and b. So, for example, gcd(12, 8) = 4, so r = 12/8 can be reduced to (12/4)/(8/4) = 3/2. The reduced form of a rational number should be in "standard form" (the denominator should always be a positive integer). If a denominator with a negative integer is present, multiply both numerator and denominator by -1 to ensure standard form is reached. For example, 3/-4 should be reduced to -3/4

Assume that the programming language you are using does not have an implementation of rational numbers.

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Source

Wikipedia