PCG64
=====

.. cpp:class:: numpy::PCG64

   Random number generation class.

Example
-------

.. code-block:: cpp

   #include <numpy/np_ndarray.h>
   using namespace numpy;

   // Use PCG64
   PCG64 obj;
   // ... operations ...

Constructors
------------

.. list-table::
   :widths: 55 25 20
   :header-rows: 1

   * - Signature
     - Location
     - Example
   * - ``PCG64(uint64_tseed = 0x853c49e6748fea9bULL, uint64_tstream = 0)``
     - NP_BITGEN.H:300
     - 

Random
------

.. list-table::
   :widths: 40 20 15 25
   :header-rows: 1

   * - Signature
     - Return Type
     - Location
     - Example
   * - ``void seed(uint64_ts)``
     - void
     - NP_BITGEN.H:322
     - :ref:`View <example-pcg64-seed-0>`

Other Methods
-------------

.. list-table::
   :widths: 40 20 15 25
   :header-rows: 1

   * - Signature
     - Return Type
     - Location
     - Example
   * - ``std::string name()``
     - std::string
     - NP_BITGEN.H:347
     - :ref:`View <example-pcg64-name-1>`
   * - ``double next_double()``
     - double
     - NP_BITGEN.H:316
     - :ref:`View <example-pcg64-next_double-2>`
   * - ``uint64_t next_uint64()``
     - uint64_t
     - NP_BITGEN.H:310
     - :ref:`View <example-pcg64-next_uint64-3>`
   * - ``uint64_t pcg_output_rxs_m_xs(uint64_tstate)``
     - uint64_t
     - NP_BITGEN.H:283
     - 
   * - ``void set_state(const std::vector<uint64_t>&state)``
     - void
     - NP_BITGEN.H:333
     - :ref:`View <example-pcg64-set_state-4>`
   * - ``void step()``
     - void
     - NP_BITGEN.H:290
     - :ref:`View <example-pcg64-step-5>`


Code Examples
-------------

The following examples are extracted from the test suite.

.. _example-pcg64-seed-0:

.. dropdown:: seed (np_test_1_all.cpp:14339)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 14329
      :emphasize-lines: 11

          }
          // std::cout << "[OK] Generator integers method\n";
      
          std::cout << " -> tests passed\n";
        }
      
        void test_vsl_reproducibility() {
          std::cout << "========= test_vsl_reproducibility ====";
      
          // Test seed reproducibility
          seed(42);
          auto arr1 = normal<double>(0.0, 1.0, { {10} });
      
          seed(42);
          auto arr2 = normal<double>(0.0, 1.0, { {10} });
      
      
      
          for (size_t i = 0; i < 10; ++i) {
            double val1 = arr1.getElementAt({ i });
            double val2 = arr2.getElementAt({ i });

.. _example-pcg64-name-1:

.. dropdown:: name (np_test_1_all.cpp:24865)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 24855
      :emphasize-lines: 11

            uint64_t before_restore = rng.next_uint64();
            rng.set_state(state);
            uint64_t after_restore = rng.next_uint64();
      
            if (before_restore != after_restore) {
              std::cout << "  [FAIL] : in np_test_bitgen_mt19937() : state restore failed";
              throw std::runtime_error("np_test_bitgen_mt19937 failed: state");
            }
      
            // Test name
            if (rng.name() != "MT19937") {
              std::cout << "  [FAIL] : in np_test_bitgen_mt19937() : incorrect name";
              throw std::runtime_error("np_test_bitgen_mt19937 failed: name");
            }
      
            std::cout << " -> tests passed" << std::endl;
          }
      
          // ============================================================================
          // PCG64 TESTS
          // ============================================================================

.. _example-pcg64-next_double-2:

.. dropdown:: next_double (np_test_1_all.cpp:24837)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 24827
      :emphasize-lines: 11

          // ============================================================================
      
          void np_test_bitgen_mt19937() {
            std::cout << "========= BitGenerator: MT19937 =======================";
      
            // Test construction
            numpy::random::MT19937 rng(12345);
      
            // Test generation
            uint64_t val1 = rng.next_uint64();
            double dval = rng.next_double();
      
            if (dval < 0.0 || dval >= 1.0) {
              std::cout << "  [FAIL] : in np_test_bitgen_mt19937() : next_double() out of range [" << dval << "]";
              throw std::runtime_error("np_test_bitgen_mt19937 failed: double range");
            }
      
            // Test seeding reproducibility
            numpy::random::MT19937 rng2(12345);
            uint64_t val2 = rng2.next_uint64();
      

.. _example-pcg64-next_uint64-3:

.. dropdown:: next_uint64 (np_test_1_all.cpp:24836)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 24826
      :emphasize-lines: 11

          // MT19937 TESTS
          // ============================================================================
      
          void np_test_bitgen_mt19937() {
            std::cout << "========= BitGenerator: MT19937 =======================";
      
            // Test construction
            numpy::random::MT19937 rng(12345);
      
            // Test generation
            uint64_t val1 = rng.next_uint64();
            double dval = rng.next_double();
      
            if (dval < 0.0 || dval >= 1.0) {
              std::cout << "  [FAIL] : in np_test_bitgen_mt19937() : next_double() out of range [" << dval << "]";
              throw std::runtime_error("np_test_bitgen_mt19937 failed: double range");
            }
      
            // Test seeding reproducibility
            numpy::random::MT19937 rng2(12345);
            uint64_t val2 = rng2.next_uint64();

.. _example-pcg64-set_state-4:

.. dropdown:: set_state (np_test_1_all.cpp:22363)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 22353
      :emphasize-lines: 11

          }
          // std::cout << "[OK] Random bytes\n";
      
          // Test state functions
          std::string state = get_state();
          if (!(!state.empty())) {
              std::string description = std::string("testRandomUtilityFunctions():") + __FILE__ + ":" + std::to_string(__LINE__) + ": !(!state.empty())";
              std::cout << std::string("[FAIL] ") + description << std::endl;
              throw std::runtime_error(description);
          }
          set_state(12345);
          // std::cout << "[OK] State functions\n";
      
          std::cout << " -> tests passed\n";
        }
      
        void testGeneratorAPI() {
          std::cout << "========= testGeneratorAPI ====";
      
          // Test modern Generator API
          auto gen = create_generator(42);

.. _example-pcg64-step-5:

.. dropdown:: step (np_test_1_all.cpp:6929)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 6919
      :emphasize-lines: 11

          // Create array of dates
          datetime64 start("2024-01-01");
          auto date_array = createDateTimeArray({5}, start);
      
          // std::cout << "Array of 5 dates initialized to 2024-01-01:" << std::endl;
          //date_array.printArray();
      
          // Create date range
          datetime64 range_start("2024-01-01");
          datetime64 range_end("2024-01-10");
          timedelta64 step(1, DateTimeUnit::Day);
      
          auto date_range = createDateRange(range_start, range_end, step);
          // std::cout << "Date range from 2024-01-01 to 2024-01-10:" << std::endl;
          //date_range.printArray();
      
          // Create timedelta array
          timedelta64 one_day(1, DateTimeUnit::Day);
          auto timedelta_array = createTimeDeltaArray({3}, one_day);
      
          // std::cout << "Array of 3 timedeltas (1 day each):" << std::endl;