Figuring out if a Float/BigDecimal is an integer

bench.rb

require 'benchmark/ips'
require 'bigdecimal'

Benchmark.ips do |x|
  x.report('BD: % 1') { num = BigDecimal(rand(1_000_000_000)); num % 1 == 0 }
  x.report('BD: == truncate') { num = BigDecimal(rand(1_000_000_000)); num.truncate == num }
  x.report('BD: frac == 0') { num = BigDecimal(rand(1_000_000_000)); num.frac == 0 }


  x.report('Float: % 1') { num = rand(1_000_000_000).to_f; num % 1 == 0 }
  x.report('Float: == truncate') { num = rand(1_000_000_000).to_f; num.truncate == num }
  # x.report('Float: frac == 0') { num = BigDecimal(rand(1_000_000_000)); num.frac == 0 }
end

res

Warming up --------------------------------------
             BD: % 1    21.427k i/100ms
     BD: == truncate    26.481k i/100ms
       BD: frac == 0    34.369k i/100ms
          Float: % 1   269.690k i/100ms
  Float: == truncate   292.471k i/100ms
Calculating -------------------------------------
             BD: % 1    215.737k (± 4.5%) i/s -      1.093M in   5.075963s
     BD: == truncate    262.966k (± 5.0%) i/s -      1.324M in   5.049044s
       BD: frac == 0    352.263k (± 4.5%) i/s -      1.787M in   5.084710s
          Float: % 1      2.669M (± 9.6%) i/s -     13.215M in   5.028862s
  Float: == truncate      3.038M (± 3.7%) i/s -     15.208M in   5.012778s