michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: //-----------------------------------------------------------------------------
michael@0: var BUGNUMBER = 363040;
michael@0: var summary = 'Array.prototype.reduce application in continued fraction';
michael@0: var actual = '';
michael@0: var expect = '';
michael@0: 
michael@0: 
michael@0: //-----------------------------------------------------------------------------
michael@0: test();
michael@0: //-----------------------------------------------------------------------------
michael@0: 
michael@0: function test()
michael@0: {
michael@0:   enterFunc ('test');
michael@0:   printBugNumber(BUGNUMBER);
michael@0:   printStatus (summary);
michael@0:  
michael@0: 
michael@0: // Print x as a continued fraction in compact abbreviated notation and return
michael@0: // the convergent [n, d] such that x - (n / d) <= epsilon.
michael@0:   function contfrac(x, epsilon) {
michael@0:     let i = Math.floor(x);
michael@0:     let a = [i];
michael@0:     x = x - i;
michael@0:     let maxerr = x;
michael@0:     while (maxerr > epsilon) {
michael@0:       x = 1 / x;
michael@0:       i = Math.floor(x);
michael@0:       a.push(i);
michael@0:       x = x - i;
michael@0:       maxerr = x * maxerr / i;
michael@0:     }
michael@0:     print(uneval(a));
michael@0:     return a.reduceRight(function (x, y) {return [x[0] * y + x[1], x[0]];}, [1, 0]);
michael@0:   }
michael@0: 
michael@0:   if (!Array.prototype.reduceRight)
michael@0:   {
michael@0:     print('Test skipped. Array.prototype.reduceRight not implemented');
michael@0:   }
michael@0:   else
michael@0:   {
michael@0: // Show contfrac in action on some interesting numbers.
michael@0:     for each (num in [Math.PI, Math.sqrt(2), 1 / (Math.sqrt(Math.E) - 1)]) {
michael@0:       print('Continued fractions for', num);
michael@0:       for each (eps in [1e-2, 1e-3, 1e-5, 1e-7, 1e-10]) {
michael@0:         let frac = contfrac(num, eps);
michael@0:         let est = frac[0] / frac[1];
michael@0:         let err = num - est;
michael@0:         print(uneval(frac), est, err);
michael@0:       }
michael@0:       print();
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   reportCompare(expect, actual, summary);
michael@0: 
michael@0:   exitFunc ('test');
michael@0: }