SVDSampler.h

/******************************************************************************
 *
 * Copyright (c) 2013-2019, Lawrence Livermore National Security, LLC
 * and other libROM project developers. See the top-level COPYRIGHT
 * file for details.
 *
 * SPDX-License-Identifier: (Apache-2.0 OR MIT)
 *
 *****************************************************************************/

// Description: An abstract class defining the interface for determining the
//              next time at which a sample should be taken for basis
//              generation using an abstract SVD algorithm.

#ifndef included_SVDSampler_h
#define included_SVDSampler_h

#include "SVD.h"

/* Use C++11 built-in shared pointers if available; else fallback to Boost. */
#if __cplusplus >= 201103L
#include <memory>
#else
#include <boost/shared_ptr.hpp>
#endif

namespace CAROM {

/**
 * Class SVDSampler defines the interface to determine the time at which the
 * next sample is needed when using an abstract SVD algorithm.
 */
class SVDSampler
{
   public:
      /**
       * @brief Constructor.
       */
      SVDSampler();

      /**
       * @brief Destructor.
       */
      ~SVDSampler();

      /**
       * @brief Returns true if it is time for the next sample.
       *
       * @param[in] time Time of interest.
       *
       * @return True if a sample should be taken at the supplied time.
       */
      virtual
      bool
      isNextSample(
         double time) = 0;

      /**
       * @brief Sample the new state, u_in.
       *
       * @pre u_in != 0
       * @pre time >= 0.0
       *
       * @param[in] u_in The state at the specified time.
       * @param[in] time The simulation time for the state.
       *
       * @return True if the sampling was successful.
       */
      bool
      takeSample(
         double* u_in,
         double time,
         bool add_without_increase = false)
      {
         return d_svd->takeSample(u_in, time, add_without_increase);
      }

      /**
       * @brief Computes next time a state sample is needed.
       *
       * @param[in] u_in The state at the specified time.
       * @param[in] rhs_in The right hand side at the specified time.
       * @param[in] time The simulation time for the state.
       *
       * @return The next time a statie sample is needed.
       */
      virtual
      double
      computeNextSampleTime(
         double* u_in,
         double* rhs_in,
         double time) = 0;

      /**
       * @brief Returns the basis vectors for the current time interval as a
       * Matrix.
       *
       * @return The basis vectors for the current time interval.
       */
      const Matrix*
      getSpatialBasis()
      {
         return d_svd->getSpatialBasis();
      }

      /**
       * @brief Returns the temporal basis vectors for the current time interval as a
       * Matrix.
       *
       * @return The temporal basis vectors for the current time interval.
       */
      const Matrix*
      getTemporalBasis()
      {
         return d_svd->getTemporalBasis();
      }

      /**
       * @brief Returns the singular values for the current time interval as a
       * Matrix.
       *
       * @return The singular values for the current time interval.
       */
      const Matrix*
      getSingularValues()
      {
         return d_svd->getSingularValues();
      }

      /**
       * @brief Returns the number of time intervals on which different sets of
       * basis vectors are defined.
       *
       * @return The number of time intervals on which there are basis vectors.
       */
      int
      getNumBasisTimeIntervals() const
      {
         return d_svd->getNumBasisTimeIntervals();
      }

      /**
       * @brief Returns the start time for the requested time interval.
       *
       * @pre 0 <= which_interval
       * @pre which_interval < getNumBasisTimeIntervals()
       *
       * @param[in] which_interval Time interval whose start time is needed.
       *
       * @return The start time for the requested time interval.
       */
      double
      getBasisIntervalStartTime(
         int which_interval) const
      {
         CAROM_ASSERT(0 <= which_interval);
         CAROM_ASSERT(which_interval < getNumBasisTimeIntervals());
         return d_svd->getBasisIntervalStartTime(which_interval);
      }

      /**
       * @brief Returns true if the next state will result in a new time
       * interval.
       *
       * @return True if the next state results in the creation of a new time
       *         interval.
       */
      bool
      isNewTimeInterval() const
      {
         return d_svd->isNewTimeInterval();
      }

      /**
       * @brief Resets sample time step.
       *
       * @param[in] new_dt New value of sample time step.
       */
      virtual
      void
      resetDt(
         double new_dt) = 0;

      /**
       * @brief Returns the dimension of the system on this processor.
       *
       * @return The dimension of the system on this processor.
       */
      int
      getDim()
      {
         return d_svd->getDim();
      }

      /**
       * @brief if true, it updates right basis vectors
       */
      bool
      isUpdateRightSV()
      {
         return d_updateRightSV;
      }

   protected:
      /**
       * @brief Pointer to the abstract SVD algorithm object.
       */
#if __cplusplus >= 201103L
      std::shared_ptr<SVD> d_svd;
#else
      boost::shared_ptr<SVD> d_svd;
#endif

      /**
       * @brief if true, isNextSample returns always true
       */
      bool d_updateRightSV;

   private:
      /**
       * @brief Unimplemented copy constructor.
       */
      SVDSampler(
         const SVDSampler& other);

      /**
       * @brief Unimplemented assignment operator.
       */
      SVDSampler&
      operator = (
         const SVDSampler& rhs);
};

}

#endif