Are there more elegant ways to prevent negative numbers in Ruby?

Question

Given that I\'d like to do the following calculation:

total = subtotal - discount

Because discount might be greater than

Answer 1

Some performance numbers:

                        user     system      total        real
[i, 0.0].max        0.806408   0.001779   0.808187 (  0.810676)
0.0 if i < 0.0      0.643962   0.001077   0.645039 (  0.646368)
0.0 if i.negative?  0.625610   0.001680   0.627290 (  0.629439)

Code:

require 'benchmark'

n = 10_000_000
Benchmark.bm do |benchmark|
  benchmark.report('[value, 0.0].max'.ljust(18)) do
    n.times do |i|
      a = [-1*i, 0.0].max
    end
  end

  benchmark.report('0.0 if value < 0.0'.ljust(18)) do
    n.times do |i|
       a = 0.0 if -1*i < 0.0 
    end
  end

  benchmark.report('0.0 if value.negative?'.ljust(18)) do
    n.times do |i|
      a = 0.0 if (-1*i).negative?
    end
  end
end