test/rand.cpp

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2015 Gael Guennebaud <gael.guennebaud@inria.fr>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#include "main.h"

typedef long long int64;

template <typename Scalar>
Scalar check_in_range(Scalar x, Scalar y) {
  Scalar r = internal::random<Scalar>(x, y);
  VERIFY(r >= x);
  if (y >= x) {
    VERIFY(r <= y);
  }
  return r;
}

template <typename Scalar>
void check_all_in_range(Scalar x, Scalar y) {
  Array<int, 1, Dynamic> mask(y - x + 1);
  mask.fill(0);
  long n = (y - x + 1) * 32;
  for (long k = 0; k < n; ++k) {
    mask(check_in_range(x, y) - x)++;
  }
  for (Index i = 0; i < mask.size(); ++i)
    if (mask(i) == 0) std::cout << "WARNING: value " << x + i << " not reached." << std::endl;
  VERIFY((mask > 0).all());
}

template <typename Scalar>
void check_histogram(Scalar x, Scalar y, int bins) {
  Array<int, 1, Dynamic> hist(bins);
  hist.fill(0);
  int f = 100000;
  int n = bins * f;
  int64 range = int64(y) - int64(x);
  int divisor = int((range + 1) / bins);
  assert(((range + 1) % bins) == 0);
  for (int k = 0; k < n; ++k) {
    Scalar r = check_in_range(x, y);
    hist(int((int64(r) - int64(x)) / divisor))++;
  }
  VERIFY((((hist.cast<double>() / double(f)) - 1.0).abs() < 0.03).all());
}

EIGEN_DECLARE_TEST(rand) {
  long long_ref = NumTraits<long>::highest() / 10;
  // the minimum guarantees that these conversions are safe
  auto char_offset = static_cast<signed char>((std::min)(g_repeat, 64));
  auto short_offset = static_cast<signed short>((std::min)(g_repeat, 8000));

  for (int i = 0; i < g_repeat * 10000; i++) {
    CALL_SUBTEST(check_in_range<float>(10, 11));
    CALL_SUBTEST(check_in_range<float>(1.24234523f, 1.24234523f));
    CALL_SUBTEST(check_in_range<float>(-1, 1));
    CALL_SUBTEST(check_in_range<float>(-1432.2352f, -1432.2352f));

    CALL_SUBTEST(check_in_range<double>(10, 11));
    CALL_SUBTEST(check_in_range<double>(1.24234523, 1.24234523));
    CALL_SUBTEST(check_in_range<double>(-1, 1));
    CALL_SUBTEST(check_in_range<double>(-1432.2352, -1432.2352));

    CALL_SUBTEST(check_in_range<int>(0, -1));
    CALL_SUBTEST(check_in_range<short>(0, -1));
    CALL_SUBTEST(check_in_range<long>(0, -1));
    CALL_SUBTEST(check_in_range<int>(-673456, 673456));
    CALL_SUBTEST(check_in_range<int>(-RAND_MAX + 10, RAND_MAX - 10));
    CALL_SUBTEST(check_in_range<short>(-24345, 24345));
    CALL_SUBTEST(check_in_range<long>(-long_ref, long_ref));
  }

  CALL_SUBTEST(check_all_in_range<signed char>(11, 11));
  CALL_SUBTEST(check_all_in_range<signed char>(11, 11 + char_offset));
  CALL_SUBTEST(check_all_in_range<signed char>(-5, 5));
  CALL_SUBTEST(check_all_in_range<signed char>(-11 - char_offset, -11));
  CALL_SUBTEST(check_all_in_range<signed char>(-126, -126 + char_offset));
  CALL_SUBTEST(check_all_in_range<signed char>(126 - char_offset, 126));
  CALL_SUBTEST(check_all_in_range<signed char>(-126, 126));

  CALL_SUBTEST(check_all_in_range<short>(11, 11));
  CALL_SUBTEST(check_all_in_range<short>(11, 11 + short_offset));
  CALL_SUBTEST(check_all_in_range<short>(-5, 5));
  CALL_SUBTEST(check_all_in_range<short>(-11 - short_offset, -11));
  CALL_SUBTEST(check_all_in_range<short>(-24345, -24345 + short_offset));
  CALL_SUBTEST(check_all_in_range<short>(24345, 24345 + short_offset));

  CALL_SUBTEST(check_all_in_range<int>(11, 11));
  CALL_SUBTEST(check_all_in_range<int>(11, 11 + g_repeat));
  CALL_SUBTEST(check_all_in_range<int>(-5, 5));
  CALL_SUBTEST(check_all_in_range<int>(-11 - g_repeat, -11));
  CALL_SUBTEST(check_all_in_range<int>(-673456, -673456 + g_repeat));
  CALL_SUBTEST(check_all_in_range<int>(673456, 673456 + g_repeat));

  CALL_SUBTEST(check_all_in_range<long>(11, 11));
  CALL_SUBTEST(check_all_in_range<long>(11, 11 + g_repeat));
  CALL_SUBTEST(check_all_in_range<long>(-5, 5));
  CALL_SUBTEST(check_all_in_range<long>(-11 - g_repeat, -11));
  CALL_SUBTEST(check_all_in_range<long>(-long_ref, -long_ref + g_repeat));
  CALL_SUBTEST(check_all_in_range<long>(long_ref, long_ref + g_repeat));

  CALL_SUBTEST(check_histogram<int>(-5, 5, 11));
  int bins = 100;
  CALL_SUBTEST(check_histogram<int>(-3333, -3333 + bins * (3333 / bins) - 1, bins));
  bins = 1000;
  CALL_SUBTEST(check_histogram<int>(-RAND_MAX + 10, -RAND_MAX + 10 + bins * (RAND_MAX / bins) - 1, bins));
  CALL_SUBTEST(
      check_histogram<int>(-RAND_MAX + 10, -int64(RAND_MAX) + 10 + bins * (2 * int64(RAND_MAX) / bins) - 1, bins));
}