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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 .
Take Down Multi-threaded Newton Method

Syntax
ok = harmonic_takedown(xout)
Purpose
This routine does the takedown for splitting the Newton method into sub-intervals.

Thread
It is assumed that this function is called by thread zero, and all the other threads have completed their work and are blocked (waiting).

xout
See multi_newton_run .

Source 

namespace {
bool multi_newton_takedown(vector<double>& xout)
{   // number of threads in the calculation
    size_t num_threads  = std::max(num_threads_, size_t(1));

    // remove duplicates and points that are not solutions
    xout.resize(0);
    bool   ok = true;
    ok       &= thread_alloc::thread_num() == 0;

    // initialize as more that sub_length_ / 2 from any possible solution
    double xlast = - sub_length_;
    for(size_t thread_num = 0; thread_num < num_threads; thread_num++)
    {   vector<double>& x = work_all_[thread_num]->x;

        size_t i;
        for(i = 0; i < x.size(); i++)
        {   // check for case where this point is lower limit for this
            // thread and upper limit for previous thread
            if( fabs(x[i] - xlast) >= sub_length_ )
            {   xout.push_back( x[i] );
                xlast = x[i];
            }
            else
            {   double fcur, flast, df;
                fun_(x[i],   fcur, df);
                fun_(xlast, flast, df);
                if( fabs(fcur) < fabs(flast) )
                {   xout[ xout.size() - 1] = x[i];
                    xlast                  = x[i];
                }
            }
        }
        // check that this thread was ok with the work it did
        ok &= work_all_[thread_num]->ok;
    }

    // go down so free memory for other threads before memory for master
    size_t thread_num = num_threads;
    while(thread_num--)
    {
# if USE_THREAD_ALLOC_FOR_WORK_ALL
        // call the destructor for vector destructor
        work_all_[thread_num]->x.~vector<double>();
        // delete the raw memory allocation
        void* v_ptr = static_cast<void*>( work_all_[thread_num] );
        thread_alloc::return_memory( v_ptr );
# else
        delete work_all_[thread_num];
# endif
        // Note that xout corresponds to memroy that is inuse by master
        // (so we can only chech have freed all their memory).
        if( thread_num > 0 )
        {   // check that there is no longer any memory inuse by this thread
            ok &= thread_alloc::inuse(thread_num) == 0;
            // return all memory being held for future use by this thread
            thread_alloc::free_available(thread_num);
        }
    }
    // now we are done with the work_all_ vector so free its memory
    // (because it is a static variable)
    work_all_.clear();

    return ok;
}
}
Input File: example/multi_thread/multi_newton.cpp