Pastable version of Tracking error in numbers

<pre class='prettyprint' language='ruby'>class ENumber
  
  attr_accessor :n, :e
  
  def initialize( number, error )
    @n = number
    @e = error
  end

# Basic arithmetic. Call like (ENumber1 + ENumber2)
  def +(o); ENumber.new(@n+o.n, @e+o.e); end
  def -(o); ENumber.new(@n-o.n, @e+o.e); end
  def *(o); ENumber.new(@n*o.n, multError(o)); end
  def /(o); ENumber.new(@n/o.n, multError(o)); end

# Trigonometric functions. Call like &quot;myENumber.cos&quot;
  def tan; trig(:tan); end
  def sin; trig(:sin); end
  def cos; trig(:cos); end

# Print this ENumber with the number and error rounded to x and y, respectively.
  # Probably should find the real way to print a +/-. since it screws up when I edit
  # this file on a terminal without UTF-8 (ie. almost any terminal)
  def to_s(x=4,y=x)
    &quot;%.#{x}fÂ±%.#{y}f&quot; % [@n, @e]
  end

private
  def trig(type)
    fcn = Math.method(type)
    ENumber.new(fcn.call(@n), 0.5*(fcn.call(@n+@e)-fcn.call(@n-@e)).abs )
  end

def multError(o)
    (@n * o.n).abs * ((@e / (@n.abs)) + (o.e / (o.n.abs)))
  end
end

# Normally this file will be included as a library.
# If it's loaded directly, run the below. Demo/example/cheap-ass-unittest.
if __FILE__ == $0
  n = ENumber.new(3,0.5)
  m = ENumber.new(4,0.25)
  
  puts (((m*n).tan)+n).to_s(5,6)
end</pre>
<a href="http://www.refactormycode.com/codes/342-tracking-error-in-numbers" style="color:#fff" title="As seen on RefactorMyCode.com"><img alt="Small_logo" src="http://www.refactormycode.com/images/small_logo.gif" style="border:0" /></a>

Refactor :my => 'code'

Recent

Popular

Pastable version of Tracking error in numbers