Rubyで絶対値を取得する
対象となる数値の絶対値を取得します。
整数の場合も小数の場合も、Numericクラスのabsメソッドを使用します。
get_absolute_value.rb 
# Get absolute value of integer
print("Absolute value of  5 is ", 5.abs, "\n")
print("Absolute value of -5 is ", (-5).abs, "\n")

# Get absolute value of float
print("Absolute value of  5.5 is ", 5.5.abs, "\n")
print("Absolute value of -5.5 is ", (-5.5).abs, "\n")
実行結果 
$ ruby get_absolute_value.rb
Absolute value of  5 is 5
Absolute value of -5 is 5
Absolute value of  5.5 is 5.5
Absolute value of -5.5 is 5.5