map a value from a range to a different domain

domainMap.rb

class DomainMap
  def setDomain(v)
    @minV = v[0].to_f
    @maxV = v[1].to_f
    self
  end

  def setRange(v)
    @minN = v[0].to_f
    @maxN = v[1].to_f
    self
  end

  def domainMap(v)
    v = v.to_f
    if (v <= @minV)
      @minN
    elsif (v >= @maxV)
      @maxN
    else
      (((@maxN - @minN) * ((v - @minV) / (@maxV - @minV))) + @minN).round(2)
    end
  end
end

skale = DomainMap.new.setDomain([1, 50]).setRange([1, 223])
puts skale.domainMap(20)