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armadillo-code/include/armadillo_bits/arma_rng.hpp
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2021-01-08 12:49:36 +10:00

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// Copyright 2008-2016 Conrad Sanderson (http://conradsanderson.id.au)
// Copyright 2008-2016 National ICT Australia (NICTA)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ------------------------------------------------------------------------
//! \addtogroup arma_rng
//! @{
#if defined(ARMA_RNG_ALT)
#undef ARMA_USE_EXTERN_RNG
#endif
#if defined(ARMA_USE_EXTERN_RNG)
extern thread_local arma_rng_cxx11 arma_rng_cxx11_instance;
// namespace { thread_local arma_rng_cxx11 arma_rng_cxx11_instance; }
#endif
class arma_rng
{
public:
#if defined(ARMA_RNG_ALT)
typedef arma_rng_alt::seed_type seed_type;
#elif defined(ARMA_USE_EXTERN_RNG)
typedef arma_rng_cxx11::seed_type seed_type;
#else
typedef arma_rng_cxx98::seed_type seed_type;
#endif
#if defined(ARMA_RNG_ALT)
static constexpr int rng_method = 2;
#elif defined(ARMA_USE_EXTERN_RNG)
static constexpr int rng_method = 1;
#else
static constexpr int rng_method = 0;
#endif
inline static void set_seed(const seed_type val);
inline static void set_seed_random();
template<typename eT> struct randi;
template<typename eT> struct randu;
template<typename eT> struct randn;
};
inline
void
arma_rng::set_seed(const arma_rng::seed_type val)
{
#if defined(ARMA_RNG_ALT)
{
arma_rng_alt::set_seed(val);
}
#elif defined(ARMA_USE_EXTERN_RNG)
{
arma_rng_cxx11_instance.set_seed(val);
}
#else
{
arma_rng_cxx98::set_seed(val);
}
#endif
}
arma_cold
inline
void
arma_rng::set_seed_random()
{
seed_type seed1 = seed_type(0);
seed_type seed2 = seed_type(0);
seed_type seed3 = seed_type(0);
seed_type seed4 = seed_type(0);
bool have_seed = false;
try
{
std::random_device rd;
if(rd.entropy() > double(0)) { seed1 = static_cast<seed_type>( rd() ); }
if(seed1 != seed_type(0)) { have_seed = true; }
}
catch(...) {}
if(have_seed == false)
{
try
{
union
{
seed_type a;
unsigned char b[sizeof(seed_type)];
} tmp;
tmp.a = seed_type(0);
std::ifstream f("/dev/urandom", std::ifstream::binary);
if(f.good()) { f.read((char*)(&(tmp.b[0])), sizeof(seed_type)); }
if(f.good())
{
seed2 = tmp.a;
if(seed2 != seed_type(0)) { have_seed = true; }
}
}
catch(...) {}
}
if(have_seed == false)
{
// get better-than-nothing seeds in case reading /dev/urandom failed
const std::chrono::system_clock::time_point tp_now = std::chrono::system_clock::now();
auto since_epoch_usec = std::chrono::duration_cast<std::chrono::microseconds>(tp_now.time_since_epoch()).count();
seed3 = static_cast<seed_type>( since_epoch_usec & 0xFFFF );
union
{
uword* a;
unsigned char b[sizeof(uword*)];
} tmp;
tmp.a = (uword*)malloc(sizeof(uword));
if(tmp.a != nullptr)
{
for(size_t i=0; i<sizeof(uword*); ++i) { seed4 += seed_type(tmp.b[i]); }
free(tmp.a);
}
}
arma_rng::set_seed( seed1 + seed2 + seed3 + seed4 );
}
template<typename eT>
struct arma_rng::randi
{
arma_inline
operator eT ()
{
#if defined(ARMA_RNG_ALT)
{
return eT( arma_rng_alt::randi_val() );
}
#elif defined(ARMA_USE_EXTERN_RNG)
{
return eT( arma_rng_cxx11_instance.randi_val() );
}
#else
{
return eT( arma_rng_cxx98::randi_val() );
}
#endif
}
inline
static
int
max_val()
{
#if defined(ARMA_RNG_ALT)
{
return arma_rng_alt::randi_max_val();
}
#elif defined(ARMA_USE_EXTERN_RNG)
{
return arma_rng_cxx11::randi_max_val();
}
#else
{
return arma_rng_cxx98::randi_max_val();
}
#endif
}
inline
static
void
fill(eT* mem, const uword N, const int a, const int b)
{
#if defined(ARMA_RNG_ALT)
{
arma_rng_alt::randi_fill(mem, N, a, b);
}
#elif defined(ARMA_USE_EXTERN_RNG)
{
arma_rng_cxx11_instance.randi_fill(mem, N, a, b);
}
#else
{
arma_rng_cxx98::randi_fill(mem, N, a, b);
}
#endif
}
};
template<typename eT>
struct arma_rng::randu
{
arma_inline
operator eT ()
{
#if defined(ARMA_RNG_ALT)
{
return eT( arma_rng_alt::randu_val() );
}
#elif defined(ARMA_USE_EXTERN_RNG)
{
return eT( arma_rng_cxx11_instance.randu_val() );
}
#else
{
return eT( arma_rng_cxx98::randu_val() );
}
#endif
}
inline
static
void
fill(eT* mem, const uword N)
{
uword j;
for(j=1; j < N; j+=2)
{
const eT tmp_i = eT( arma_rng::randu<eT>() );
const eT tmp_j = eT( arma_rng::randu<eT>() );
(*mem) = tmp_i; mem++;
(*mem) = tmp_j; mem++;
}
if((j-1) < N)
{
(*mem) = eT( arma_rng::randu<eT>() );
}
}
};
template<typename T>
struct arma_rng::randu< std::complex<T> >
{
arma_inline
operator std::complex<T> ()
{
const T a = T( arma_rng::randu<T>() );
const T b = T( arma_rng::randu<T>() );
return std::complex<T>(a, b);
}
inline
static
void
fill(std::complex<T>* mem, const uword N)
{
for(uword i=0; i < N; ++i)
{
const T a = T( arma_rng::randu<T>() );
const T b = T( arma_rng::randu<T>() );
mem[i] = std::complex<T>(a, b);
}
}
};
template<typename eT>
struct arma_rng::randn
{
inline
operator eT () const
{
#if defined(ARMA_RNG_ALT)
{
return eT( arma_rng_alt::randn_val() );
}
#elif defined(ARMA_USE_EXTERN_RNG)
{
return eT( arma_rng_cxx11_instance.randn_val() );
}
#else
{
return eT( arma_rng_cxx98::randn_val() );
}
#endif
}
inline
static
void
dual_val(eT& out1, eT& out2)
{
#if defined(ARMA_RNG_ALT)
{
arma_rng_alt::randn_dual_val(out1, out2);
}
#elif defined(ARMA_USE_EXTERN_RNG)
{
arma_rng_cxx11_instance.randn_dual_val(out1, out2);
}
#else
{
arma_rng_cxx98::randn_dual_val(out1, out2);
}
#endif
}
inline
static
void
fill_simple(eT* mem, const uword N)
{
uword i, j;
for(i=0, j=1; j < N; i+=2, j+=2)
{
arma_rng::randn<eT>::dual_val( mem[i], mem[j] );
}
if(i < N)
{
mem[i] = eT( arma_rng::randn<eT>() );
}
}
inline
static
void
fill(eT* mem, const uword N)
{
#if defined(ARMA_USE_OPENMP)
{
if((N < 1024) || omp_in_parallel()) { arma_rng::randn<eT>::fill_simple(mem, N); return; }
typedef std::mt19937_64::result_type seed_type;
const uword n_threads = uword( mp_thread_limit::get() );
std::vector< std::mt19937_64 > engine(n_threads);
std::vector< std::normal_distribution<double> > distr(n_threads);
for(uword t=0; t < n_threads; ++t)
{
std::mt19937_64& t_engine = engine[t];
t_engine.seed( seed_type(t) + seed_type(arma_rng::randi<seed_type>()) );
}
const uword chunk_size = N / n_threads;
#pragma omp parallel for schedule(static) num_threads(int(n_threads))
for(uword t=0; t < n_threads; ++t)
{
const uword start = (t+0) * chunk_size;
const uword endp1 = (t+1) * chunk_size;
std::mt19937_64& t_engine = engine[t];
std::normal_distribution<double>& t_distr = distr[t];
for(uword i=start; i < endp1; ++i) { mem[i] = eT( t_distr(t_engine)); }
}
std::mt19937_64& t0_engine = engine[0];
std::normal_distribution<double>& t0_distr = distr[0];
for(uword i=(n_threads*chunk_size); i < N; ++i) { mem[i] = eT( t0_distr(t0_engine)); }
}
#else
{
arma_rng::randn<eT>::fill_simple(mem, N);
}
#endif
}
};
template<typename T>
struct arma_rng::randn< std::complex<T> >
{
inline
operator std::complex<T> () const
{
#if defined(_MSC_VER)
// attempt at workaround for MSVC bug
// does MS even test their so-called compilers before release?
T a;
T b;
#else
T a(0);
T b(0);
#endif
arma_rng::randn<T>::dual_val(a, b);
return std::complex<T>(a, b);
}
inline
static
void
dual_val(std::complex<T>& out1, std::complex<T>& out2)
{
#if defined(_MSC_VER)
T a;
T b;
#else
T a(0);
T b(0);
#endif
arma_rng::randn<T>::dual_val(a,b);
out1 = std::complex<T>(a,b);
arma_rng::randn<T>::dual_val(a,b);
out2 = std::complex<T>(a,b);
}
inline
static
void
fill_simple(std::complex<T>* mem, const uword N)
{
for(uword i=0; i < N; ++i)
{
mem[i] = std::complex<T>( arma_rng::randn< std::complex<T> >() );
}
}
inline
static
void
fill(std::complex<T>* mem, const uword N)
{
#if defined(ARMA_USE_OPENMP)
{
if((N < 512) || omp_in_parallel()) { arma_rng::randn< std::complex<T> >::fill_simple(mem, N); return; }
typedef std::mt19937_64::result_type seed_type;
const uword n_threads = uword( mp_thread_limit::get() );
std::vector< std::mt19937_64 > engine(n_threads);
std::vector< std::normal_distribution<double> > distr(n_threads);
for(uword t=0; t < n_threads; ++t)
{
std::mt19937_64& t_engine = engine[t];
t_engine.seed( seed_type(t) + seed_type(arma_rng::randi<seed_type>()) );
}
const uword chunk_size = N / n_threads;
#pragma omp parallel for schedule(static) num_threads(int(n_threads))
for(uword t=0; t < n_threads; ++t)
{
const uword start = (t+0) * chunk_size;
const uword endp1 = (t+1) * chunk_size;
std::mt19937_64& t_engine = engine[t];
std::normal_distribution<double>& t_distr = distr[t];
for(uword i=start; i < endp1; ++i)
{
const T val1 = T( t_distr(t_engine) );
const T val2 = T( t_distr(t_engine) );
mem[i] = std::complex<T>(val1, val2);
}
}
std::mt19937_64& t0_engine = engine[0];
std::normal_distribution<double>& t0_distr = distr[0];
for(uword i=(n_threads*chunk_size); i < N; ++i)
{
const T val1 = T( t0_distr(t0_engine) );
const T val2 = T( t0_distr(t0_engine) );
mem[i] = std::complex<T>(val1, val2);
}
}
#else
{
arma_rng::randn< std::complex<T> >::fill_simple(mem, N);
}
#endif
}
};
//! @}