Function sparse_matrix_vector_multiply

dlib/svm/sparse_vector.h:1022–1051

    template <typename EXP, typename T, long NR, long NC, typename MM, typename L>
    void sparse_matrix_vector_multiply (
        const std::vector<sample_pair>& edges,
        const matrix_exp<EXP>& v,
        matrix<T,NR,NC,MM,L>& result
    )
    {
        // make sure requires clause is not broken
        DLIB_ASSERT(max_index_plus_one(edges) <= (unsigned long)v.size() &&
                    is_col_vector(v),
                    "\t void sparse_matrix_vector_multiply()"
                    << "\n\t Invalid inputs were given to this function"
                    << "\n\t max_index_plus_one(edges): " << max_index_plus_one(edges)
                    << "\n\t v.size():                  " << v.size() 
                    << "\n\t is_col_vector(v):          " << is_col_vector(v) 
        );

        result.set_size(v.nr(),v.nc());
        result = 0;

        for (unsigned long k = 0; k < edges.size(); ++k)
        {
            const long i = edges[k].index1();
            const long j = edges[k].index2();
            const double d = edges[k].distance();

            result(i) += v(j)*d;
            if (i != j)
                result(j) += v(i)*d;
        }
    }

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