/data/development/ViennaCL/dev/viennacl/toeplitz_matrix.hpp

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#ifndef VIENNACL_TOEPLITZ_MATRIX_HPP
#define VIENNACL_TOEPLITZ_MATRIX_HPP

/* =========================================================================
   Copyright (c) 2010-2011, Institute for Microelectronics,
                            Institute for Analysis and Scientific Computing,
                            TU Wien.

                            -----------------
                  ViennaCL - The Vienna Computing Library
                            -----------------

   Project Head:    Karl Rupp                   rupp@iue.tuwien.ac.at
               
   (A list of authors and contributors can be found in the PDF manual)

   License:         MIT (X11), see file LICENSE in the base directory
============================================================================= */

#include "viennacl/forwards.h"
#include "viennacl/vector.hpp"
#include "viennacl/ocl/context.hpp"

#include "viennacl/fft.hpp"

#include "viennacl/linalg/toeplitz_matrix_operations.hpp"


namespace viennacl {

    template<class SCALARTYPE, unsigned int ALIGNMENT>
    class toeplitz_matrix
    {
      public:

        explicit toeplitz_matrix()
        {
          viennacl::linalg::kernels::fft<SCALARTYPE, 1>::init();
        }

        explicit toeplitz_matrix(std::size_t rows, std::size_t cols) : elements_(rows * 2)
        {
          assert(rows == cols && "Toeplitz matrix must be square!");
          viennacl::linalg::kernels::fft<SCALARTYPE, 1>::init();
        }
        

        void resize(size_t sz, bool preserve = true) {
            elements_.resize(sz * 2, preserve);
        }

        viennacl::ocl::handle<cl_mem> handle() const { return elements_.handle(); }

        viennacl::vector<SCALARTYPE, ALIGNMENT> & elements() { return elements_; }
        viennacl::vector<SCALARTYPE, ALIGNMENT> const & elements() const { return elements_; }


        std::size_t size1() const { return elements_.size() / 2; }
        
        std::size_t size2() const { return elements_.size() / 2; }

        std::size_t internal_size() const { return elements_.internal_size(); }


        entry_proxy<SCALARTYPE> operator()(std::size_t row_index, std::size_t col_index) 
        {
            assert(row_index < size1() && col_index < size2() && "Invalid access");
            
            int index = static_cast<int>(col_index) - static_cast<int>(row_index);
            
            if (index < 0)
              index = -index;
            else if
              (index > 0) index = 2 * size1() - index;
            return elements_[index];
        }


        toeplitz_matrix<SCALARTYPE, ALIGNMENT>& operator +=(toeplitz_matrix<SCALARTYPE, ALIGNMENT>& that) {
            elements_ += that.elements();
            return *this;
        }

    private:
        toeplitz_matrix(toeplitz_matrix const & t) {}
        toeplitz_matrix & operator=(toeplitz_matrix const & t) {}
        
      
        viennacl::vector<SCALARTYPE, ALIGNMENT> elements_;
    };

    template <typename SCALARTYPE, unsigned int ALIGNMENT>
    void copy(std::vector<SCALARTYPE> const & cpu_vec, toeplitz_matrix<SCALARTYPE, ALIGNMENT>& gpu_mat)
    {
        std::size_t size = gpu_mat.size1();
        assert((size * 2 - 1)  == cpu_vec.size() && "Size mismatch");
        std::vector<SCALARTYPE> rvrs(cpu_vec.size());
        std::copy(cpu_vec.begin(), cpu_vec.end(), rvrs.begin());
        std::reverse(rvrs.begin(), rvrs.end());

        std::vector<SCALARTYPE> tmp(size * 2);
        std::copy(rvrs.begin() + size - 1, rvrs.end(), tmp.begin());
        std::copy(rvrs.begin(), rvrs.begin() + size - 1, tmp.begin() + size + 1);
        tmp[size] = 0.0;
        copy(tmp, gpu_mat.elements());
    }

    template <typename SCALARTYPE, unsigned int ALIGNMENT>
    void copy(toeplitz_matrix<SCALARTYPE, ALIGNMENT> const & gpu_mat, std::vector<SCALARTYPE> & cpu_vec)
    {
        std::size_t size = gpu_mat.size1();
        assert((size * 2 - 1)  == cpu_vec.size() && "Size mismatch");
        std::vector<SCALARTYPE> tmp(size * 2);
        copy(gpu_mat.elements(), tmp);
        std::reverse(tmp.begin(), tmp.end());

        std::copy(tmp.begin(), tmp.begin() + size - 1, cpu_vec.begin() + size);
        std::copy(tmp.begin() + size, tmp.end(), cpu_vec.begin());

    }

    template <typename SCALARTYPE, unsigned int ALIGNMENT, typename MATRIXTYPE>
    void copy(toeplitz_matrix<SCALARTYPE, ALIGNMENT> const & tep_src, MATRIXTYPE & com_dst)
    {
        std::size_t size = tep_src.size1();
        assert(size == com_dst.size1() && "Size mismatch");
        assert(size == com_dst.size2() && "Size mismatch");
        std::vector<SCALARTYPE> tmp(tep_src.size1() * 2 - 1);
        copy(tep_src, tmp);

        for(std::size_t i = 0; i < size; i++)
            for(std::size_t j = 0; j < size; j++)
                com_dst(i, j) = tmp[static_cast<int>(j) - static_cast<int>(i) + static_cast<int>(size) - 1];
    }

    template <typename SCALARTYPE, unsigned int ALIGNMENT, typename MATRIXTYPE>
    void copy(MATRIXTYPE const & com_src, toeplitz_matrix<SCALARTYPE, ALIGNMENT>& tep_dst)
    {
        std::size_t size = tep_dst.size1();
        assert(size == com_src.size1() && "Size mismatch");
        assert(size == com_src.size2() && "Size mismatch");

        std::vector<SCALARTYPE> tmp(2*size - 1);

        for(int i = size - 1; i >= 0; i--)
            tmp[size - i - 1] = com_src(i, 0);

        for(std::size_t i = 1; i < size; i++)
            tmp[size + i - 1] = com_src(0, i);

        copy(tmp, tep_dst);
    }

    /*template <typename SCALARTYPE, unsigned int ALIGNMENT, unsigned int VECTOR_ALIGNMENT>
    void prod_impl(toeplitz_matrix<SCALARTYPE, ALIGNMENT>& mat,
                   vector<SCALARTYPE, VECTOR_ALIGNMENT>& vec,
                   vector<SCALARTYPE, VECTOR_ALIGNMENT>& result) {
        viennacl::vector<SCALARTYPE, VECTOR_ALIGNMENT> tep(mat.elements().size() * 2);
        fft::real_to_complex(mat.elements(), tep, mat.elements().size());

        viennacl::vector<SCALARTYPE, VECTOR_ALIGNMENT> tmp(vec.size() * 4);
        viennacl::vector<SCALARTYPE, VECTOR_ALIGNMENT> tmp2(vec.size() * 4);

        tmp.clear();
        copy(vec, tmp);
        fft::real_to_complex(tmp, tmp2, vec.size() * 2);
        fft::convolve(tep, tmp2, tmp);
        fft::complex_to_real(tmp, tmp2, vec.size() * 2);
        copy(tmp2.begin(), tmp2.begin() + vec.size(), result.begin());
    }*/

    template<class SCALARTYPE, unsigned int ALIGNMENT>
    std::ostream & operator<<(std::ostream & s, toeplitz_matrix<SCALARTYPE, ALIGNMENT>& gpu_matrix)
    {
        std::size_t size = gpu_matrix.size1();
        std::vector<SCALARTYPE> tmp(2*size - 1);
        copy(gpu_matrix, tmp);
        s << "[" << size << "," << size << "](";

        for(std::size_t i = 0; i < size; i++) {
            s << "(";
            for(std::size_t j = 0; j < size; j++) {
                s << tmp[(int)j - (int)i + (int)size - 1];
                //s << (int)i - (int)j;
                if(j < (size - 1)) s << ",";
            }
            s << ")";
        }
        s << ")";
        return s;
    }

}

#endif // _VIENNACL_TOEPLITZ_MATRIX_HPP