Live Calculator + Math module using ruby and sinatra

this calculator will open port 3000 using sinatra and listen on two
paths the root (http://localhost:3000/) to load the calculator HTML
and /calc path (http://localhost:3000/calc) to evaluate expression

when you write any expression such as (2+2) javascrip will send the
expression as you type to /calc path and get teh result into a div with
id=result

i included the Math module so you can use cos, sin, tan and any method
within the ruby Math Module.

also as this calculator uses eval method you can use it to evaluate a
pure ruby expression such as "Emad "*10 this will print "Emad" 10 times

have fun and let me know how did you use it ;)

Gist: https://gist.github.com/9565542