function isApprox( t, actual, expected, rtol ) {
	var delta;
	var tol;
	var i;

	t.strictEqual( actual.length, expected.length, 'returns expected value' );
	for ( i = 0; i < expected.length; i++ ) {
		if ( actual[ i ] === expected[ i ] ) {
			t.strictEqual( actual[ i ], expected[ i ], 'returns expected value' );
		} else {
			delta = abs( actual[ i ] - expected[ i ] );
			tol = rtol * EPS * abs( expected[ i ] );
			t.ok( delta <= tol, 'within tolerance. actual: '+actual[ i ]+'. expected: '+expected[ i ]+'. delta: '+delta+'. tol: '+tol+'.' );
		}
	}
}
Tests for element-wise approximate equality.

@private
@param {Object} t - test object
@param {Collection} actual - actual values
@param {Collection} expected - expected values
@param {number} rtol - relative tolerance