Ruby class for solving integrals

integral.rb

class Integral
  def initialize(a, b, n = 100_000)
    @a, @b, @n = a, b, n
  end

  def definite
    h = (@b - @a).fdiv @n
    h * (0...@n).inject(0) { |f, i| f + yield(@a + i * h) }
  end
end

Integral.new(0, 2, 1000).definite { |x| Math.sin(x) * Math.cos(x) } # => 0.41378875524886966
Integral.new(0.1, 1).definite { |x| Math.log(x) / x } # => -2.65105267379091