comparison DEPENDENCIES/generic/include/boost/random/inversive_congruential.hpp @ 16:2665513ce2d3

Add boost headers

+/* boost random/inversive_congruential.hpp header file
+ *
+ * Copyright Jens Maurer 2000-2001
+ * Distributed under the Boost Software License, Version 1.0. (See
+ * accompanying file LICENSE_1_0.txt or copy at
+ * http://www.boost.org/LICENSE_1_0.txt)
+ *
+ * See http://www.boost.org for most recent version including documentation.
+ *
+ * $Id: inversive_congruential.hpp 71018 2011-04-05 21:27:52Z steven_watanabe $
+ *
+ * Revision history
+ *  2001-02-18  moved to individual header files
+ */
+
+#ifndef BOOST_RANDOM_INVERSIVE_CONGRUENTIAL_HPP
+#define BOOST_RANDOM_INVERSIVE_CONGRUENTIAL_HPP
+
+#include <iosfwd>
+#include <stdexcept>
+#include <boost/assert.hpp>
+#include <boost/config.hpp>
+#include <boost/cstdint.hpp>
+#include <boost/integer/static_log2.hpp>
+#include <boost/random/detail/config.hpp>
+#include <boost/random/detail/const_mod.hpp>
+#include <boost/random/detail/seed.hpp>
+#include <boost/random/detail/operators.hpp>
+#include <boost/random/detail/seed_impl.hpp>
+
+#include <boost/random/detail/disable_warnings.hpp>
+
+namespace boost {
+namespace random {
+
+// Eichenauer and Lehn 1986
+/**
+ * Instantiations of class template @c inversive_congruential_engine model a
+ * \pseudo_random_number_generator. It uses the inversive congruential
+ * algorithm (ICG) described in
+ *
+ *  @blockquote
+ *  "Inversive pseudorandom number generators: concepts, results and links",
+ *  Peter Hellekalek, In: "Proceedings of the 1995 Winter Simulation
+ *  Conference", C. Alexopoulos, K. Kang, W.R. Lilegdon, and D. Goldsman
+ *  (editors), 1995, pp. 255-262. ftp://random.mat.sbg.ac.at/pub/data/wsc95.ps
+ *  @endblockquote
+ *
+ * The output sequence is defined by x(n+1) = (a*inv(x(n)) - b) (mod p),
+ * where x(0), a, b, and the prime number p are parameters of the generator.
+ * The expression inv(k) denotes the multiplicative inverse of k in the
+ * field of integer numbers modulo p, with inv(0) := 0.
+ *
+ * The template parameter IntType shall denote a signed integral type large
+ * enough to hold p; a, b, and p are the parameters of the generators. The
+ * template parameter val is the validation value checked by validation.
+ *
+ * @xmlnote
+ * The implementation currently uses the Euclidian Algorithm to compute
+ * the multiplicative inverse. Therefore, the inversive generators are about
+ * 10-20 times slower than the others (see section"performance"). However,
+ * the paper talks of only 3x slowdown, so the Euclidian Algorithm is probably
+ * not optimal for calculating the multiplicative inverse.
+ * @endxmlnote
+ */
+template<class IntType, IntType a, IntType b, IntType p>
+class inversive_congruential_engine
+{
+public:
+    typedef IntType result_type;
+    BOOST_STATIC_CONSTANT(bool, has_fixed_range = false);
+
+    BOOST_STATIC_CONSTANT(result_type, multiplier = a);
+    BOOST_STATIC_CONSTANT(result_type, increment = b);
+    BOOST_STATIC_CONSTANT(result_type, modulus = p);
+    BOOST_STATIC_CONSTANT(IntType, default_seed = 1);
+
+    static result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () { return b == 0 ? 1 : 0; }
+    static result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () { return p-1; }
+    
+    /**
+     * Constructs an @c inversive_congruential_engine, seeding it with
+     * the default seed.
+     */
+    inversive_congruential_engine() { seed(); }
+
+    /**
+     * Constructs an @c inversive_congruential_engine, seeding it with @c x0.
+     */
+    BOOST_RANDOM_DETAIL_ARITHMETIC_CONSTRUCTOR(inversive_congruential_engine,
+                                               IntType, x0)
+    { seed(x0); }
+    
+    /**
+     * Constructs an @c inversive_congruential_engine, seeding it with values
+     * produced by a call to @c seq.generate().
+     */
+    BOOST_RANDOM_DETAIL_SEED_SEQ_CONSTRUCTOR(inversive_congruential_engine,
+                                             SeedSeq, seq)
+    { seed(seq); }
+    
+    /**
+     * Constructs an @c inversive_congruential_engine, seeds it
+     * with values taken from the itrator range [first, last),
+     * and adjusts first to point to the element after the last one
+     * used.  If there are not enough elements, throws @c std::invalid_argument.
+     *
+     * first and last must be input iterators.
+     */
+    template<class It> inversive_congruential_engine(It& first, It last)
+    { seed(first, last); }
+
+    /**
+     * Calls seed(default_seed)
+     */
+    void seed() { seed(default_seed); }
+  
+    /**
+     * If c mod m is zero and x0 mod m is zero, changes the current value of
+     * the generator to 1. Otherwise, changes it to x0 mod m. If c is zero,
+     * distinct seeds in the range [1,m) will leave the generator in distinct
+     * states. If c is not zero, the range is [0,m).
+     */
+    BOOST_RANDOM_DETAIL_ARITHMETIC_SEED(inversive_congruential_engine, IntType, x0)
+    {
+        // wrap _x if it doesn't fit in the destination
+        if(modulus == 0) {
+            _value = x0;
+        } else {
+            _value = x0 % modulus;
+        }
+        // handle negative seeds
+        if(_value <= 0 && _value != 0) {
+            _value += modulus;
+        }
+        // adjust to the correct range
+        if(increment == 0 && _value == 0) {
+            _value = 1;
+        }
+        BOOST_ASSERT(_value >= (min)());
+        BOOST_ASSERT(_value <= (max)());
+    }
+
+    /**
+     * Seeds an @c inversive_congruential_engine using values from a SeedSeq.
+     */
+    BOOST_RANDOM_DETAIL_SEED_SEQ_SEED(inversive_congruential_engine, SeedSeq, seq)
+    { seed(detail::seed_one_int<IntType, modulus>(seq)); }
+    
+    /**
+     * seeds an @c inversive_congruential_engine with values taken
+     * from the itrator range [first, last) and adjusts @c first to
+     * point to the element after the last one used.  If there are
+     * not enough elements, throws @c std::invalid_argument.
+     *
+     * @c first and @c last must be input iterators.
+     */
+    template<class It> void seed(It& first, It last)
+    { seed(detail::get_one_int<IntType, modulus>(first, last)); }
+
+    /** Returns the next output of the generator. */
+    IntType operator()()
+    {
+        typedef const_mod<IntType, p> do_mod;
+        _value = do_mod::mult_add(a, do_mod::invert(_value), b);
+        return _value;
+    }
+  
+    /** Fills a range with random values */
+    template<class Iter>
+    void generate(Iter first, Iter last)
+    { detail::generate_from_int(*this, first, last); }
+
+    /** Advances the state of the generator by @c z. */
+    void discard(boost::uintmax_t z)
+    {
+        for(boost::uintmax_t j = 0; j < z; ++j) {
+            (*this)();
+        }
+    }
+
+    /**
+     * Writes the textual representation of the generator to a @c std::ostream.
+     */
+    BOOST_RANDOM_DETAIL_OSTREAM_OPERATOR(os, inversive_congruential_engine, x)
+    {
+        os << x._value;
+        return os;
+    }
+
+    /**
+     * Reads the textual representation of the generator from a @c std::istream.
+     */
+    BOOST_RANDOM_DETAIL_ISTREAM_OPERATOR(is, inversive_congruential_engine, x)
+    {
+        is >> x._value;
+        return is;
+    }
+
+    /**
+     * Returns true if the two generators will produce identical
+     * sequences of outputs.
+     */
+    BOOST_RANDOM_DETAIL_EQUALITY_OPERATOR(inversive_congruential_engine, x, y)
+    { return x._value == y._value; }
+
+    /**
+     * Returns true if the two generators will produce different
+     * sequences of outputs.
+     */
+    BOOST_RANDOM_DETAIL_INEQUALITY_OPERATOR(inversive_congruential_engine)
+
+private:
+    IntType _value;
+};
+
+#ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
+//  A definition is required even for integral static constants
+template<class IntType, IntType a, IntType b, IntType p>
+const bool inversive_congruential_engine<IntType, a, b, p>::has_fixed_range;
+template<class IntType, IntType a, IntType b, IntType p>
+const typename inversive_congruential_engine<IntType, a, b, p>::result_type inversive_congruential_engine<IntType, a, b, p>::multiplier;
+template<class IntType, IntType a, IntType b, IntType p>
+const typename inversive_congruential_engine<IntType, a, b, p>::result_type inversive_congruential_engine<IntType, a, b, p>::increment;
+template<class IntType, IntType a, IntType b, IntType p>
+const typename inversive_congruential_engine<IntType, a, b, p>::result_type inversive_congruential_engine<IntType, a, b, p>::modulus;
+template<class IntType, IntType a, IntType b, IntType p>
+const typename inversive_congruential_engine<IntType, a, b, p>::result_type inversive_congruential_engine<IntType, a, b, p>::default_seed;
+#endif
+
+/// \cond show_deprecated
+
+// provided for backwards compatibility
+template<class IntType, IntType a, IntType b, IntType p, IntType val = 0>
+class inversive_congruential : public inversive_congruential_engine<IntType, a, b, p>
+{
+    typedef inversive_congruential_engine<IntType, a, b, p> base_type;
+public:
+    inversive_congruential(IntType x0 = 1) : base_type(x0) {}
+    template<class It>
+    inversive_congruential(It& first, It last) : base_type(first, last) {}
+};
+
+/// \endcond
+
+/**
+ * The specialization hellekalek1995 was suggested in
+ *
+ *  @blockquote
+ *  "Inversive pseudorandom number generators: concepts, results and links",
+ *  Peter Hellekalek, In: "Proceedings of the 1995 Winter Simulation
+ *  Conference", C. Alexopoulos, K. Kang, W.R. Lilegdon, and D. Goldsman
+ *  (editors), 1995, pp. 255-262. ftp://random.mat.sbg.ac.at/pub/data/wsc95.ps
+ *  @endblockquote
+ */
+typedef inversive_congruential_engine<uint32_t, 9102, 2147483647-36884165,
+  2147483647> hellekalek1995;
+
+} // namespace random
+
+using random::hellekalek1995;
+
+} // namespace boost
+
+#include <boost/random/detail/enable_warnings.hpp>
+
+#endif // BOOST_RANDOM_INVERSIVE_CONGRUENTIAL_HPP