libstdc++-v3/testsuite/20_util/hash/chi2_q_uniform_random.cc

   1 // { dg-options "-std=gnu++0x" }
   2 // Use smaller statistics when running on simulators, so it takes less time.
   3 // For powerpc-eabi, SAMPLES=30000 fails.
   4 // { dg-options "-std=gnu++0x -DSAMPLES=35000" { target simulator } }
   5
   6 // Copyright (C) 2010-2014 Free Software Foundation, Inc.
   7 //
   8 // This file is part of the GNU ISO C++ Library.  This library is free
   9 // software; you can redistribute it and/or modify it under the
  10 // terms of the GNU General Public License as published by the
  11 // Free Software Foundation; either version 3, or (at your option)
  12 // any later version.
  13 //
  14 // This library is distributed in the hope that it will be useful,
  15 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 // GNU General Public License for more details.
  18 //
  19 // You should have received a copy of the GNU General Public License
  20 // along with this library; see the file COPYING3.  If not see
  21 // <http://www.gnu.org/licenses/>.
  22
  23 #include "chi2_quality.h"
  24
  25 // Tests chi^2 for a distribution of uniformly generated random strings.
  26 void
  27 test_uniform_random()
  28 {
  29   bool test __attribute__((unused)) = true;
  30   std::srand(137);
  31   std::unordered_set<std::string> set;
  32   std::string s;
  33   const unsigned long N = SAMPLES;
  34   const unsigned long k = N/100;
  35   const unsigned int len = 25;
  36   while (set.size() < N)
  37     {
  38       s.clear();
  39       for (unsigned int i = 0; i < len; ++i)
  40        s.push_back(rand() % 128);
  41       set.insert(s);
  42     }
  43
  44   double chi2 = chi2_hash(set, k);
  45   VERIFY( chi2 < k*1.1 );
  46 }
  47
  48 int
  49 main()
  50 {
  51   test_uniform_random();
  52   return 0;
  53 }