// 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');
}
//
//////////////////////////////////////////////////////////////////////////////
