text: // Copyright 2009 the Sputnik authors.  All rights reserved.
  // This code is governed by the BSD license found in the LICENSE file.
  
  /*---
  info: Closures are admitted
  es5id: 13.2.1_A5_T2
  description: >
      Returning a function that approximates the derivative of f  using
      an interval of dx, which should be appropriately small
  ---*/
  
  // Return a function that approximates the derivative of f
  // using an interval of dx, which should be appropriately small.
  function derivative(f, dx) {
      return function(x) {
        return (f(x + dx) - f(x)) / dx;
      };
  }
  
  //////////////////////////////////////////////////////////////////////////////
  //CHECK#1
  if (Math.abs(derivative(Math.sin, 0.0001)(0) - derivative(Math.sin, 0.0001)(2*Math.PI)) >= 1/65536.0) {
  	$ERROR('#1: Math.abs(derivative(Math.sin, 0.0001)(0) - derivative(Math.sin, 0.0001)(2*Math.PI)) <= 1/65536.0');
  }
  //
  //////////////////////////////////////////////////////////////////////////////
  