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@(@\newcommand{\W}[1]{ \; #1 \; } \newcommand{\R}[1]{ {\rm #1} } \newcommand{\B}[1]{ {\bf #1} } \newcommand{\D}[2]{ \frac{\partial #1}{\partial #2} } \newcommand{\DD}[3]{ \frac{\partial^2 #1}{\partial #2 \partial #3} } \newcommand{\Dpow}[2]{ \frac{\partial^{#1}}{\partial {#2}^{#1}} } \newcommand{\dpow}[2]{ \frac{ {\rm d}^{#1}}{{\rm d}\, {#2}^{#1}} }@)@This is cppad-20221105 documentation. Here is a link to its current documentation .
Atomic Matrix Multiply Forward Type Calculation: Example Implementation

Purpose
The for_type routine overrides the virtual functions used by the atomic_four base; see for_type .

Source 

# include <cppad/example/atomic_four/mat_mul/mat_mul.hpp>

namespace CppAD { // BEGIN_CPPAD_NAMESPACE
//
// for_type override
template <class Base>
bool atomic_mat_mul<Base>::for_type(
    size_t                                     call_id     ,
    const CppAD::vector<CppAD::ad_type_enum>&  type_x      ,
    CppAD::vector<CppAD::ad_type_enum>&        type_y      )
{
    //
    // n_left, n_middle, n_right
    size_t n_left, n_middle, n_right;
    get(call_id, n_left, n_middle, n_right);
# ifndef NDEBUG
    // n, m
    size_t n     = type_x.size();
    size_t m     = type_y.size();
    //
    // check sizes
    assert( n == n_left * n_middle + n_middle * n_right );
    assert( m == n_left * n_right );
# endif
    //
    // offset
    size_t offset = n_left * n_middle;
    //
    // type_y
    // y[ i * n_right + j] = sum_k
    //      x[i * n_middle + k] * x[ offset + k * n_right + j]
    // treat multpilication by zero like absolute zero
    for(size_t i = 0; i < n_left; ++i)
    {   for(size_t j = 0; j < n_right; ++j)
        {   CppAD::ad_type_enum type_ij = CppAD::identical_zero_enum;
            for(size_t k = 0; k < n_middle; ++k)
            {   CppAD::ad_type_enum type_ik = type_x[i * n_middle + k];
                CppAD::ad_type_enum type_kj = type_x[offset + k * n_right + j];
                if( type_ik != identical_zero_enum )
                {   if( type_kj != identical_zero_enum )
                    {   type_ij = std::max(type_ij, type_ik);
                        type_ij = std::max(type_ij, type_kj);
                    }
                }
            }
            type_y[ i * n_right + j] = type_ij;
        }
    }
    return true;
}
} // END_CPPAD_NAMESPACE
Input File: include/cppad/example/atomic_four/mat_mul/for_type.hpp