diff --git a/Eigen/src/Core/MathFunctions.h b/Eigen/src/Core/MathFunctions.h
index 0be29bc..3f5df7b 100644
--- a/Eigen/src/Core/MathFunctions.h
+++ b/Eigen/src/Core/MathFunctions.h
@@ -563,34 +563,6 @@
   }
 };
 
-/****************************************************************************
- * Implementation of random                                               *
- ****************************************************************************/
-
-template <typename Scalar, bool IsComplex, bool IsInteger>
-struct random_default_impl {};
-
-template <typename Scalar>
-struct random_impl : random_default_impl<Scalar, NumTraits<Scalar>::IsComplex, NumTraits<Scalar>::IsInteger> {};
-
-template <typename Scalar>
-struct random_retval {
-  typedef Scalar type;
-};
-
-template <typename Scalar>
-inline EIGEN_MATHFUNC_RETVAL(random, Scalar) random(const Scalar& x, const Scalar& y);
-template <typename Scalar>
-inline EIGEN_MATHFUNC_RETVAL(random, Scalar) random();
-
-template <typename Scalar>
-struct random_default_impl<Scalar, false, false> {
-  static inline Scalar run(const Scalar& x, const Scalar& y) {
-    return x + (y - x) * Scalar(std::rand()) / Scalar(RAND_MAX);
-  }
-  static inline Scalar run() { return run(Scalar(NumTraits<Scalar>::IsSigned ? -1 : 0), Scalar(1)); }
-};
-
 enum { meta_floor_log2_terminate, meta_floor_log2_move_up, meta_floor_log2_move_down, meta_floor_log2_bogus };
 
 template <unsigned int n, int lower, int upper>
@@ -769,56 +741,166 @@
 
 #endif  // EIGEN_COMP_GNUC || EIGEN_COMP_CLANG
 
+template <typename BitsType>
+int log2_ceil(BitsType x) {
+  int n = CHAR_BIT * sizeof(BitsType) - clz(x);
+  bool powerOfTwo = (x & (x - 1)) == 0;
+  return x == 0 ? 0 : powerOfTwo ? n - 1 : n;
+}
+
+template <typename BitsType>
+int log2_floor(BitsType x) {
+  int n = CHAR_BIT * sizeof(BitsType) - clz(x);
+  return x == 0 ? 0 : n - 1;
+}
+
+/****************************************************************************
+ * Implementation of random                                               *
+ ****************************************************************************/
+
+// return a Scalar filled with numRandomBits beginning from the least significant bit
+template <typename Scalar>
+Scalar getRandomBits(int numRandomBits) {
+  using BitsType = typename numext::get_integer_by_size<sizeof(Scalar)>::unsigned_type;
+  enum : int {
+    StdRandBits = meta_floor_log2<(unsigned int)(RAND_MAX) + 1>::value,
+    ScalarBits = sizeof(Scalar) * CHAR_BIT
+  };
+  eigen_assert((numRandomBits >= 0) && (numRandomBits <= ScalarBits));
+  const BitsType mask = BitsType(-1) >> (ScalarBits - numRandomBits);
+  BitsType randomBits = BitsType(0);
+  for (int shift = 0; shift < numRandomBits; shift += StdRandBits) {
+    int r = std::rand();
+    randomBits |= static_cast<BitsType>(r) << shift;
+  }
+  // clear the excess bits
+  randomBits &= mask;
+  return numext::bit_cast<Scalar, BitsType>(randomBits);
+}
+
+template <typename Scalar, bool IsComplex, bool IsInteger>
+struct random_default_impl {};
+
+template <typename Scalar>
+struct random_impl : random_default_impl<Scalar, NumTraits<Scalar>::IsComplex, NumTraits<Scalar>::IsInteger> {};
+
+template <typename Scalar>
+struct random_retval {
+  typedef Scalar type;
+};
+
+template <typename Scalar>
+inline EIGEN_MATHFUNC_RETVAL(random, Scalar) random(const Scalar& x, const Scalar& y);
+template <typename Scalar>
+inline EIGEN_MATHFUNC_RETVAL(random, Scalar) random();
+
+template <typename Scalar>
+struct random_default_impl<Scalar, false, false> {
+  using BitsType = typename numext::get_integer_by_size<sizeof(Scalar)>::unsigned_type;
+  enum : int { MantissaBits = NumTraits<Scalar>::digits() - 1 };
+  static EIGEN_DEVICE_FUNC inline Scalar run(const Scalar& x, const Scalar& y, int numRandomBits = MantissaBits) {
+    Scalar half_x = Scalar(0.5) * x;
+    Scalar half_y = Scalar(0.5) * y;
+    Scalar result = (half_x + half_y) + (half_y - half_x) * run(numRandomBits);
+    // result is in the half-open interval [x, y) -- provided that x < y
+    return result;
+  }
+  static EIGEN_DEVICE_FUNC inline Scalar run(int numRandomBits = MantissaBits) {
+    eigen_assert(numRandomBits >= 0 && numRandomBits <= MantissaBits);
+    BitsType randomBits = getRandomBits<BitsType>(numRandomBits);
+    // if fewer than MantissaBits is requested, shift them to the left
+    randomBits <<= (MantissaBits - numRandomBits);
+    // randomBits is in the half-open interval [2,4)
+    randomBits |= numext::bit_cast<BitsType>(Scalar(2));
+    // result is in the half-open interval [-1,1)
+    Scalar result = numext::bit_cast<Scalar>(randomBits) - Scalar(3);
+    return result;
+  }
+};
+
+// TODO: fix this for PPC
+template <bool Specialize = sizeof(long double) == 2 * sizeof(uint64_t) && !EIGEN_ARCH_PPC>
+struct random_longdouble_impl {
+  enum : int {
+    Size = sizeof(long double),
+    MantissaBits = NumTraits<long double>::digits() - 1,
+    LowBits = MantissaBits > 64 ? 64 : MantissaBits,
+    HighBits = MantissaBits > 64 ? MantissaBits - 64 : 0
+  };
+  static EIGEN_DEVICE_FUNC inline long double run() {
+    EIGEN_USING_STD(memcpy)
+    uint64_t randomBits[2];
+    long double result = 2.0L;
+    memcpy(&randomBits, &result, Size);
+    randomBits[0] |= getRandomBits<uint64_t>(LowBits);
+    randomBits[1] |= getRandomBits<uint64_t>(HighBits);
+    memcpy(&result, &randomBits, Size);
+    result -= 3.0L;
+    return result;
+  }
+};
+template <>
+struct random_longdouble_impl<false> {
+  using Impl = random_impl<double>;
+  static EIGEN_DEVICE_FUNC inline long double run() { return static_cast<long double>(Impl::run()); }
+};
+
+template <>
+struct random_impl<long double> {
+  static EIGEN_DEVICE_FUNC inline long double run(const long double& x, const long double& y) {
+    long double half_x = 0.5L * x;
+    long double half_y = 0.5L * y;
+    long double result = (half_x + half_y) + (half_y - half_x) * run();
+    return result;
+  }
+  static EIGEN_DEVICE_FUNC inline long double run() { return random_longdouble_impl<>::run(); }
+};
+
 template <typename Scalar>
 struct random_default_impl<Scalar, false, true> {
-  static inline Scalar run(const Scalar& x, const Scalar& y) {
+  using BitsType = typename numext::get_integer_by_size<sizeof(Scalar)>::unsigned_type;
+  enum : int { ScalarBits = sizeof(Scalar) * CHAR_BIT };
+  static EIGEN_DEVICE_FUNC inline Scalar run(const Scalar& x, const Scalar& y) {
     if (y <= x) return x;
-    // ScalarU is the unsigned counterpart of Scalar, possibly Scalar itself.
-    typedef typename make_unsigned<Scalar>::type ScalarU;
-    // ScalarX is the widest of ScalarU and unsigned int.
-    // We'll deal only with ScalarX and unsigned int below thus avoiding signed
-    // types and arithmetic and signed overflows (which are undefined behavior).
-    typedef std::conditional_t<(ScalarU(-1) > unsigned(-1)), ScalarU, unsigned> ScalarX;
-    // The following difference doesn't overflow, provided our integer types are two's
-    // complement and have the same number of padding bits in signed and unsigned variants.
-    // This is the case in most modern implementations of C++.
-    ScalarX range = ScalarX(y) - ScalarX(x);
-    ScalarX offset = 0;
-    ScalarX divisor = 1;
-    ScalarX multiplier = 1;
-    const unsigned rand_max = RAND_MAX;
-    if (range <= rand_max)
-      divisor = (rand_max + 1) / (range + 1);
-    else
-      multiplier = 1 + range / (rand_max + 1);
-    // Rejection sampling.
+    const BitsType range = static_cast<BitsType>(y) - static_cast<BitsType>(x) + 1;
+    // handle edge case where [x,y] spans the entire range of Scalar
+    if (range == 0) return getRandomBits<Scalar>(ScalarBits);
+    // calculate the number of random bits needed to fill range
+    const int numRandomBits = log2_ceil(range);
+    BitsType randomBits;
     do {
-      offset = (unsigned(std::rand()) * multiplier) / divisor;
-    } while (offset > range);
-    return Scalar(ScalarX(x) + offset);
+      randomBits = getRandomBits<BitsType>(numRandomBits);
+      // if the random draw is outside [0, range), try again (rejection sampling)
+      // in the worst-case scenario, the probability of rejection is: 1/2 - 1/2^numRandomBits < 50%
+    } while (randomBits >= range);
+    Scalar result = x + static_cast<Scalar>(randomBits);
+    return result;
   }
 
-  static inline Scalar run() {
+  static EIGEN_DEVICE_FUNC inline Scalar run() {
 #ifdef EIGEN_MAKING_DOCS
     return run(Scalar(NumTraits<Scalar>::IsSigned ? -10 : 0), Scalar(10));
 #else
-    enum {
-      rand_bits = meta_floor_log2<(unsigned int)(RAND_MAX) + 1>::value,
-      scalar_bits = sizeof(Scalar) * CHAR_BIT,
-      shift = plain_enum_max(0, int(rand_bits) - int(scalar_bits)),
-      offset = NumTraits<Scalar>::IsSigned ? (1 << (plain_enum_min(rand_bits, scalar_bits) - 1)) : 0
-    };
-    return Scalar((std::rand() >> shift) - offset);
+    return getRandomBits<Scalar>(ScalarBits);
 #endif
   }
 };
 
+template <>
+struct random_impl<bool> {
+  static EIGEN_DEVICE_FUNC inline bool run(const bool& x, const bool& y) {
+    if (y <= x) return x;
+    return run();
+  }
+  static EIGEN_DEVICE_FUNC inline bool run() { return getRandomBits<int>(1) ? true : false; }
+};
+
 template <typename Scalar>
 struct random_default_impl<Scalar, true, false> {
-  static inline Scalar run(const Scalar& x, const Scalar& y) {
+  static EIGEN_DEVICE_FUNC inline Scalar run(const Scalar& x, const Scalar& y) {
     return Scalar(random(x.real(), y.real()), random(x.imag(), y.imag()));
   }
-  static inline Scalar run() {
+  static EIGEN_DEVICE_FUNC inline Scalar run() {
     typedef typename NumTraits<Scalar>::Real RealScalar;
     return Scalar(random<RealScalar>(), random<RealScalar>());
   }
@@ -1864,13 +1946,6 @@
 ******************************************/
 
 template <>
-struct random_impl<bool> {
-  static inline bool run() { return random<int>(0, 1) == 0 ? false : true; }
-
-  static inline bool run(const bool& a, const bool& b) { return random<int>(a, b) == 0 ? false : true; }
-};
-
-template <>
 struct scalar_fuzzy_impl<bool> {
   typedef bool RealScalar;
 
diff --git a/Eigen/src/Core/NumTraits.h b/Eigen/src/Core/NumTraits.h
index 80f74e9..2848b78 100644
--- a/Eigen/src/Core/NumTraits.h
+++ b/Eigen/src/Core/NumTraits.h
@@ -206,9 +206,7 @@
 
   EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR static inline T highest() { return (numext::numeric_limits<T>::max)(); }
 
-  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR static inline T lowest() {
-    return IsInteger ? (numext::numeric_limits<T>::min)() : static_cast<T>(-(numext::numeric_limits<T>::max)());
-  }
+  EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR static inline T lowest() { return (numext::numeric_limits<T>::lowest)(); }
 
   EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR static inline T infinity() { return numext::numeric_limits<T>::infinity(); }
 
diff --git a/Eigen/src/Core/arch/Default/BFloat16.h b/Eigen/src/Core/arch/Default/BFloat16.h
index 68b48f9..be44909 100644
--- a/Eigen/src/Core/arch/Default/BFloat16.h
+++ b/Eigen/src/Core/arch/Default/BFloat16.h
@@ -677,16 +677,22 @@
 namespace internal {
 
 template <>
-struct random_default_impl<bfloat16, false, false> {
-  static inline bfloat16 run(const bfloat16& x, const bfloat16& y) {
-    return x + (y - x) * bfloat16(float(std::rand()) / float(RAND_MAX));
-  }
-  static inline bfloat16 run() { return run(bfloat16(-1.f), bfloat16(1.f)); }
+struct is_arithmetic<bfloat16> {
+  enum { value = true };
 };
 
 template <>
-struct is_arithmetic<bfloat16> {
-  enum { value = true };
+struct random_impl<bfloat16> {
+  enum : int { MantissaBits = 7 };
+  using Impl = random_impl<float>;
+  static EIGEN_DEVICE_FUNC inline bfloat16 run(const bfloat16& x, const bfloat16& y) {
+    float result = Impl::run(x, y, MantissaBits);
+    return bfloat16(result);
+  }
+  static EIGEN_DEVICE_FUNC inline bfloat16 run() {
+    float result = Impl::run(MantissaBits);
+    return bfloat16(result);
+  }
 };
 
 }  // namespace internal
diff --git a/Eigen/src/Core/arch/Default/Half.h b/Eigen/src/Core/arch/Default/Half.h
index 92516c7..17d534d 100644
--- a/Eigen/src/Core/arch/Default/Half.h
+++ b/Eigen/src/Core/arch/Default/Half.h
@@ -762,16 +762,22 @@
 namespace internal {
 
 template <>
-struct random_default_impl<half, false, false> {
-  static inline half run(const half& x, const half& y) {
-    return x + (y - x) * half(float(std::rand()) / float(RAND_MAX));
-  }
-  static inline half run() { return run(half(-1.f), half(1.f)); }
+struct is_arithmetic<half> {
+  enum { value = true };
 };
 
 template <>
-struct is_arithmetic<half> {
-  enum { value = true };
+struct random_impl<half> {
+  enum : int { MantissaBits = 10 };
+  using Impl = random_impl<float>;
+  static EIGEN_DEVICE_FUNC inline half run(const half& x, const half& y) {
+    float result = Impl::run(x, y, MantissaBits);
+    return half(result);
+  }
+  static EIGEN_DEVICE_FUNC inline half run() {
+    float result = Impl::run(MantissaBits);
+    return half(result);
+  }
 };
 
 }  // end namespace internal
diff --git a/test/AnnoyingScalar.h b/test/AnnoyingScalar.h
index b4f77ad..637fdbf 100644
--- a/test/AnnoyingScalar.h
+++ b/test/AnnoyingScalar.h
@@ -183,6 +183,20 @@
 EIGEN_STRONG_INLINE float cast(const AnnoyingScalar& x) {
   return *x.v;
 }
+
+template <>
+struct random_impl<AnnoyingScalar> {
+  using Impl = random_impl<float>;
+  static EIGEN_DEVICE_FUNC inline AnnoyingScalar run(const AnnoyingScalar& x, const AnnoyingScalar& y) {
+    float result = Impl::run(*x.v, *y.v);
+    return AnnoyingScalar(result);
+  }
+  static EIGEN_DEVICE_FUNC inline AnnoyingScalar run() {
+    float result = Impl::run();
+    return AnnoyingScalar(result);
+  }
+};
+
 }  // namespace internal
 }  // namespace Eigen
 
diff --git a/test/MovableScalar.h b/test/MovableScalar.h
index 52591bc..56a873e 100644
--- a/test/MovableScalar.h
+++ b/test/MovableScalar.h
@@ -28,6 +28,23 @@
 
 template <>
 struct NumTraits<MovableScalar<float>> : GenericNumTraits<float> {};
+
+namespace internal {
+template <typename T>
+struct random_impl<MovableScalar<T>> {
+  using MoveableT = MovableScalar<T>;
+  using Impl = random_impl<T>;
+  static EIGEN_DEVICE_FUNC inline MoveableT run(const MoveableT& x, const MoveableT& y) {
+    T result = Impl::run(x, y);
+    return MoveableT(result);
+  }
+  static EIGEN_DEVICE_FUNC inline MoveableT run() {
+    T result = Impl::run();
+    return MoveableT(result);
+  }
+};
+}  // namespace internal
+
 }  // namespace Eigen
 
 #endif
diff --git a/test/SafeScalar.h b/test/SafeScalar.h
index 2079af4..4f4da56 100644
--- a/test/SafeScalar.h
+++ b/test/SafeScalar.h
@@ -26,3 +26,21 @@
   T val_;
   bool initialized_;
 };
+
+namespace Eigen {
+namespace internal {
+template <typename T>
+struct random_impl<SafeScalar<T>> {
+  using SafeT = SafeScalar<T>;
+  using Impl = random_impl<T>;
+  static EIGEN_DEVICE_FUNC inline SafeT run(const SafeT& x, const SafeT& y) {
+    T result = Impl::run(x, y);
+    return SafeT(result);
+  }
+  static EIGEN_DEVICE_FUNC inline SafeT run() {
+    T result = Impl::run();
+    return SafeT(result);
+  }
+};
+}  // namespace internal
+}  // namespace Eigen
diff --git a/test/geo_alignedbox.cpp b/test/geo_alignedbox.cpp
index 266e58b..f335b34 100644
--- a/test/geo_alignedbox.cpp
+++ b/test/geo_alignedbox.cpp
@@ -36,10 +36,10 @@
 
   const Index dim = box.dim();
 
-  VectorType p0 = VectorType::Random(dim);
-  VectorType p1 = VectorType::Random(dim);
+  VectorType p0 = VectorType::Random(dim) / Scalar(2);
+  VectorType p1 = VectorType::Random(dim) / Scalar(2);
   while (p1 == p0) {
-    p1 = VectorType::Random(dim);
+    p1 = VectorType::Random(dim) / Scalar(2);
   }
   RealScalar s1 = internal::random<RealScalar>(0, 1);
 
@@ -216,7 +216,7 @@
 Matrix<Scalar, Dim, (1 << Dim)> boxGetCorners(const Matrix<Scalar, Dim, 1>& min_, const Matrix<Scalar, Dim, 1>& max_) {
   Matrix<Scalar, Dim, (1 << Dim)> result;
   for (Index i = 0; i < (1 << Dim); ++i) {
-    for (Index j = 0; j < Dim; ++j) result(j, i) = (i & (1 << j)) ? min_(j) : max_(j);
+    for (Index j = 0; j < Dim; ++j) result(j, i) = (i & (Index(1) << j)) ? min_(j) : max_(j);
   }
   return result;
 }
diff --git a/test/rand.cpp b/test/rand.cpp
index 2b193ff..bb90ad9 100644
--- a/test/rand.cpp
+++ b/test/rand.cpp
@@ -7,10 +7,9 @@
 // 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 <cstdlib>
 #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);
@@ -25,8 +24,8 @@
 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) {
+  int64_t n = (y - x + 1) * 32;
+  for (int64_t k = 0; k < n; ++k) {
     mask(check_in_range(x, y) - x)++;
   }
   for (Index i = 0; i < mask.size(); ++i)
@@ -34,82 +33,203 @@
   VERIFY((mask > 0).all());
 }
 
+template <typename Scalar, typename EnableIf = void>
+class HistogramHelper {
+ public:
+  HistogramHelper(int nbins) : HistogramHelper(Scalar(-1), Scalar(1), nbins) {}
+  HistogramHelper(Scalar lower, Scalar upper, int nbins) {
+    lower_ = static_cast<double>(lower);
+    upper_ = static_cast<double>(upper);
+    num_bins_ = nbins;
+    bin_width_ = (upper_ - lower_) / static_cast<double>(nbins);
+  }
+  int bin(Scalar v) {
+    double result = (static_cast<double>(v) - lower_) / bin_width_;
+    return std::min<int>(static_cast<int>(result), num_bins_ - 1);
+  }
+
+  double uniform_bin_probability(int bin) {
+    double range = upper_ - lower_;
+    if (bin < num_bins_ - 1) {
+      return bin_width_ / range;
+    }
+    return (upper_ - (lower_ + double(bin) * bin_width_)) / range;
+  }
+
+ private:
+  double lower_;
+  double upper_;
+  int num_bins_;
+  double bin_width_;
+};
+
+template <typename Scalar>
+class HistogramHelper<Scalar, std::enable_if_t<Eigen::NumTraits<Scalar>::IsInteger>> {
+ public:
+  using RangeType = typename Eigen::internal::make_unsigned<Scalar>::type;
+  HistogramHelper(int nbins)
+      : HistogramHelper(Eigen::NumTraits<Scalar>::lowest(), Eigen::NumTraits<Scalar>::highest(), nbins) {}
+  HistogramHelper(Scalar lower, Scalar upper, int nbins)
+      : lower_{lower}, upper_{upper}, num_bins_{nbins}, bin_width_{bin_width(lower, upper, nbins)} {}
+
+  int bin(Scalar v) { return static_cast<int>(RangeType(v - lower_) / bin_width_); }
+
+  double uniform_bin_probability(int bin) {
+    // Avoid overflow in computing range.
+    double range = static_cast<double>(RangeType(upper_ - lower_)) + 1.0;
+    if (bin < num_bins_ - 1) {
+      return static_cast<double>(bin_width_) / range;
+    }
+    return static_cast<double>(RangeType(upper_) - RangeType((lower_ + bin * bin_width_)) + 1) / range;
+  }
+
+ private:
+  static constexpr Scalar bin_width(Scalar lower, Scalar upper, int nbins) {
+    // Avoid overflow in computing the full range.
+    return RangeType(upper - nbins - lower + 1) / nbins + 1;
+  }
+
+  Scalar lower_;
+  Scalar upper_;
+  int num_bins_;
+  Scalar bin_width_;
+};
+
 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) {
+  Eigen::VectorXd hist = Eigen::VectorXd::Zero(bins);
+  HistogramHelper<Scalar> hist_helper(x, y, bins);
+  int64_t n = static_cast<int64_t>(bins) * 10000;  // Approx 10000 per bin.
+  for (int64_t k = 0; k < n; ++k) {
     Scalar r = check_in_range(x, y);
-    hist(int((int64(r) - int64(x)) / divisor))++;
+    int bin = hist_helper.bin(r);
+    hist(bin)++;
   }
-  VERIFY((((hist.cast<double>() / double(f)) - 1.0).abs() < 0.03).all());
+  // Normalize bins by probability.
+  for (int i = 0; i < bins; ++i) {
+    hist(i) = hist(i) / n / hist_helper.uniform_bin_probability(i);
+  }
+  VERIFY(((hist.array() - 1.0).abs() < 0.05).all());
+}
+
+template <typename Scalar>
+void check_histogram(int bins) {
+  Eigen::VectorXd hist = Eigen::VectorXd::Zero(bins);
+  HistogramHelper<Scalar> hist_helper(bins);
+  int64_t n = static_cast<int64_t>(bins) * 10000;  // Approx 10000 per bin.
+  for (int64_t k = 0; k < n; ++k) {
+    Scalar r = Eigen::internal::random<Scalar>();
+    int bin = hist_helper.bin(r);
+    hist(bin)++;
+  }
+  // Normalize bins by probability.
+  for (int i = 0; i < bins; ++i) {
+    hist(i) = hist(i) / n / hist_helper.uniform_bin_probability(i);
+  }
+  VERIFY(((hist.array() - 1.0).abs() < 0.05).all());
 }
 
 EIGEN_DECLARE_TEST(rand) {
-  long long_ref = NumTraits<long>::highest() / 10;
+  int64_t int64_ref = NumTraits<int64_t>::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));
+  int8_t int8t_offset = static_cast<int8_t>((std::min)(g_repeat, 64));
+  int16_t int16t_offset = static_cast<int16_t>((std::min)(g_repeat, 8000));
+  EIGEN_UNUSED_VARIABLE(int64_ref);
+  EIGEN_UNUSED_VARIABLE(int8t_offset);
+  EIGEN_UNUSED_VARIABLE(int16t_offset);
 
   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_1(check_in_range<float>(10.0f, 11.0f));
+    CALL_SUBTEST_1(check_in_range<float>(1.24234523f, 1.24234523f));
+    CALL_SUBTEST_1(check_in_range<float>(-1.0f, 1.0f));
+    CALL_SUBTEST_1(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_2(check_in_range<double>(10.0, 11.0));
+    CALL_SUBTEST_2(check_in_range<double>(1.24234523, 1.24234523));
+    CALL_SUBTEST_2(check_in_range<double>(-1.0, 1.0));
+    CALL_SUBTEST_2(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_3(check_in_range<long double>(10.0L, 11.0L));
+    CALL_SUBTEST_3(check_in_range<long double>(1.24234523L, 1.24234523L));
+    CALL_SUBTEST_3(check_in_range<long double>(-1.0L, 1.0L));
+    CALL_SUBTEST_3(check_in_range<long double>(-1432.2352L, -1432.2352L));
+
+    CALL_SUBTEST_4(check_in_range<half>(half(10.0f), half(11.0f)));
+    CALL_SUBTEST_4(check_in_range<half>(half(1.24234523f), half(1.24234523f)));
+    CALL_SUBTEST_4(check_in_range<half>(half(-1.0f), half(1.0f)));
+    CALL_SUBTEST_4(check_in_range<half>(half(-1432.2352f), half(-1432.2352f)));
+
+    CALL_SUBTEST_5(check_in_range<bfloat16>(bfloat16(10.0f), bfloat16(11.0f)));
+    CALL_SUBTEST_5(check_in_range<bfloat16>(bfloat16(1.24234523f), bfloat16(1.24234523f)));
+    CALL_SUBTEST_5(check_in_range<bfloat16>(bfloat16(-1.0f), bfloat16(1.0f)));
+    CALL_SUBTEST_5(check_in_range<bfloat16>(bfloat16(-1432.2352f), bfloat16(-1432.2352f)));
+
+    CALL_SUBTEST_6(check_in_range<int32_t>(0, -1));
+    CALL_SUBTEST_6(check_in_range<int16_t>(0, -1));
+    CALL_SUBTEST_6(check_in_range<int64_t>(0, -1));
+    CALL_SUBTEST_6(check_in_range<int32_t>(-673456, 673456));
+    CALL_SUBTEST_6(check_in_range<int32_t>(-RAND_MAX + 10, RAND_MAX - 10));
+    CALL_SUBTEST_6(check_in_range<int16_t>(-24345, 24345));
+    CALL_SUBTEST_6(check_in_range<int64_t>(-int64_ref, int64_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_7(check_all_in_range<int8_t>(11, 11));
+  CALL_SUBTEST_7(check_all_in_range<int8_t>(11, 11 + int8t_offset));
+  CALL_SUBTEST_7(check_all_in_range<int8_t>(-5, 5));
+  CALL_SUBTEST_7(check_all_in_range<int8_t>(-11 - int8t_offset, -11));
+  CALL_SUBTEST_7(check_all_in_range<int8_t>(-126, -126 + int8t_offset));
+  CALL_SUBTEST_7(check_all_in_range<int8_t>(126 - int8t_offset, 126));
+  CALL_SUBTEST_7(check_all_in_range<int8_t>(-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_8(check_all_in_range<int16_t>(11, 11));
+  CALL_SUBTEST_8(check_all_in_range<int16_t>(11, 11 + int16t_offset));
+  CALL_SUBTEST_8(check_all_in_range<int16_t>(-5, 5));
+  CALL_SUBTEST_8(check_all_in_range<int16_t>(-11 - int16t_offset, -11));
+  CALL_SUBTEST_8(check_all_in_range<int16_t>(-24345, -24345 + int16t_offset));
+  CALL_SUBTEST_8(check_all_in_range<int16_t>(24345, 24345 + int16t_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_9(check_all_in_range<int32_t>(11, 11));
+  CALL_SUBTEST_9(check_all_in_range<int32_t>(11, 11 + g_repeat));
+  CALL_SUBTEST_9(check_all_in_range<int32_t>(-5, 5));
+  CALL_SUBTEST_9(check_all_in_range<int32_t>(-11 - g_repeat, -11));
+  CALL_SUBTEST_9(check_all_in_range<int32_t>(-673456, -673456 + g_repeat));
+  CALL_SUBTEST_9(check_all_in_range<int32_t>(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_10(check_all_in_range<int64_t>(11, 11));
+  CALL_SUBTEST_10(check_all_in_range<int64_t>(11, 11 + g_repeat));
+  CALL_SUBTEST_10(check_all_in_range<int64_t>(-5, 5));
+  CALL_SUBTEST_10(check_all_in_range<int64_t>(-11 - g_repeat, -11));
+  CALL_SUBTEST_10(check_all_in_range<int64_t>(-int64_ref, -int64_ref + g_repeat));
+  CALL_SUBTEST_10(check_all_in_range<int64_t>(int64_ref, int64_ref + g_repeat));
 
-  CALL_SUBTEST(check_histogram<int>(-5, 5, 11));
+  CALL_SUBTEST_11(check_histogram<int32_t>(-5, 5, 11));
   int bins = 100;
-  CALL_SUBTEST(check_histogram<int>(-3333, -3333 + bins * (3333 / bins) - 1, bins));
+  EIGEN_UNUSED_VARIABLE(bins)
+  CALL_SUBTEST_11(check_histogram<int32_t>(-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));
+  CALL_SUBTEST_11(check_histogram<int32_t>(-RAND_MAX + 10, -RAND_MAX + 10 + bins * (RAND_MAX / bins) - 1, bins));
+  CALL_SUBTEST_11(check_histogram<int32_t>(-RAND_MAX + 10,
+                                           -int64_t(RAND_MAX) + 10 + bins * (2 * int64_t(RAND_MAX) / bins) - 1, bins));
+
+  CALL_SUBTEST_12(check_histogram<uint8_t>(/*bins=*/16));
+  CALL_SUBTEST_12(check_histogram<uint16_t>(/*bins=*/1024));
+  CALL_SUBTEST_12(check_histogram<uint32_t>(/*bins=*/1024));
+  CALL_SUBTEST_12(check_histogram<uint64_t>(/*bins=*/1024));
+
+  CALL_SUBTEST_13(check_histogram<int8_t>(/*bins=*/16));
+  CALL_SUBTEST_13(check_histogram<int16_t>(/*bins=*/1024));
+  CALL_SUBTEST_13(check_histogram<int32_t>(/*bins=*/1024));
+  CALL_SUBTEST_13(check_histogram<int64_t>(/*bins=*/1024));
+
+  CALL_SUBTEST_14(check_histogram<float>(-10.0f, 10.0f, /*bins=*/1024));
+  CALL_SUBTEST_14(check_histogram<double>(-10.0, 10.0, /*bins=*/1024));
+  CALL_SUBTEST_14(check_histogram<long double>(-10.0L, 10.0L, /*bins=*/1024));
+  CALL_SUBTEST_14(check_histogram<half>(half(-10.0f), half(10.0f), /*bins=*/512));
+  CALL_SUBTEST_14(check_histogram<bfloat16>(bfloat16(-10.0f), bfloat16(10.0f), /*bins=*/64));
+
+  CALL_SUBTEST_15(check_histogram<float>(/*bins=*/1024));
+  CALL_SUBTEST_15(check_histogram<double>(/*bins=*/1024));
+  CALL_SUBTEST_15(check_histogram<long double>(/*bins=*/1024));
+  CALL_SUBTEST_15(check_histogram<half>(/*bins=*/512));
+  CALL_SUBTEST_15(check_histogram<bfloat16>(/*bins=*/64));
 }