InitialConditionVariableToSimulation.cpp

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#include <polyfem/optimization/var2sims/InitialConditionVariableToSimulation.hpp>
 
#include <polyfem/optimization/AdjointTools.hpp>
#include <polyfem/optimization/VarFormDiff.hpp>
#include <polyfem/optimization/var2sims/ActiveSelectionUtils.hpp>
#include <polyfem/utils/Logger.hpp>
 
#include <Eigen/Core>
 
#include <cassert>
#include <string>
 
namespace polyfem::solver
{
 
    InitialConditionVariableToSimulation::InitialConditionVariableToSimulation(VarFormPtrs varforms,
                                                                               DiffCachePtrs diff_caches,
                                                                               CompositeParametrization parametrizations,
                                                                               Eigen::VectorXi active_dofs)
        : dof_num_(varforms[0]->primary_space().ndof()),
          varforms_(std::move(varforms)),
          diff_caches_(std::move(diff_caches)),
          parametrization_(std::move(parametrizations)),
          active_dofs_(std::move(active_dofs))
    {
        assert(!varforms_.empty());
        assert(varforms_.size() == diff_caches_.size());
 
        for (auto &varform : varforms_)
        {
            if (!varform->get_problem().is_time_dependent())
            {
                log_and_throw_adjoint_error("Fail to construct initial condition variable to simulation. Reason: Static problem not supported.");
            }
        }
 
        // Validate active selection.
        std::string reason;
        if (!is_active_dofs_valid(active_dofs_, varforms_, reason))
        {
            log_and_throw_adjoint_error("Fail to construct initial condition variable to simulation. Reason: {}", reason);
        }
 
        // Expand implicit all active selection.
        if (active_dofs_.size() == 0)
        {
            active_dofs_ = Eigen::VectorXi::LinSpaced(dof_num_, 0, dof_num_ - 1);
        }
 
        // Populate baseline initial-condition override for each varform.
        for (int i = 0; i < varforms_.size(); ++i)
        {
            Eigen::MatrixXd sol, vel;
            varforms_[i]->initial_solution(sol);
            varforms_[i]->initial_velocity(vel);
 
            // initial condition might return history of position and velocity.
            // Since we can't handle that, drop all condition from prev time steps.
            if (sol.cols() > 1)
            {
                sol.conservativeResize(Eigen::NoChange, 1);
            }
            if (vel.cols() > 1)
            {
                vel.conservativeResize(Eigen::NoChange, 1);
            }
 
            if (sol.rows() != dof_num_ || sol.cols() != 1)
            {
                log_and_throw_adjoint_error("Fail to construct initial condition variable to simulation. Reason: Invalid initial solution shape ({}, {}). Expect ({}, 1).",
                                            sol.rows(), sol.cols(), dof_num_);
            }
            if (vel.rows() != dof_num_ || vel.cols() != 1)
            {
                log_and_throw_adjoint_error("Fail to construct initial condition variable to simulation. Reason: Invalid initial velocity shape ({}, {}). Expect ({}, 1).",
                                            vel.rows(), vel.cols(), dof_num_);
            }
 
            diff_caches_[i]->initial_condition_override = varform::InitialConditionOverride{
                sol, vel, {}};
        }
    }
 
    std::string InitialConditionVariableToSimulation::name() const
    {
        return "initial";
    }
 
    ParameterType InitialConditionVariableToSimulation::parameter_type() const
    {
        return ParameterType::InitialCondition;
    }
 
    bool InitialConditionVariableToSimulation::affects_varform(const varform::DifferentiableVarForm &target) const
    {
        for (const auto &varform : varforms_)
        {
            if (varform.get() == &target)
            {
                return true;
            }
        }
        return false;
    }
 
    void InitialConditionVariableToSimulation::update(const Eigen::VectorXd &x)
    {
        Eigen::VectorXd y = parametrization_.eval(x);
        assert(y.size() == para_out_dof());
 
        int active_num = active_dofs_.size();
        for (auto &dc : diff_caches_)
        {
            // Override should already be populated in the constructor.
            assert(dc->initial_condition_override && "Initial-condition optimization must initialize its override");
            auto &initial_condition_override = *dc->initial_condition_override;
            auto &sol = initial_condition_override.solution;
            auto &vel = initial_condition_override.velocity;
            assert(sol.rows() == dof_num_ && sol.cols() >= 1 && "Initial solution override must match the simulation DOFs");
            assert(vel.rows() == dof_num_ && vel.cols() >= 1 && "Initial velocity override must match the simulation DOFs");
 
            for (int i = 0; i < active_num; ++i)
            {
                sol(active_dofs_(i), 0) = y(i);
                vel(active_dofs_(i), 0) = y(active_num + i);
            }
 
            initial_condition_override.acceleration = {};
        }
    }
 
    void InitialConditionVariableToSimulation::update_state_variables(const Eigen::VectorXd &x, Eigen::VectorXd &state_variables) const
    {
        assert(state_variables.size() == 2 * dof_num_);
 
        Eigen::VectorXd y = parametrization_.eval(x);
        assert(y.size() == para_out_dof());
 
        int active_num = active_dofs_.size();
        for (int i = 0; i < active_num; ++i)
        {
            state_variables(active_dofs_(i)) = y(i);
            state_variables(dof_num_ + active_dofs_(i)) = y(active_num + i);
        }
    }
 
    Eigen::VectorXd InitialConditionVariableToSimulation::compute_adjoint_term(const Eigen::VectorXd &x) const
    {
        Eigen::VectorXd term, cur_term;
        for (int i = 0; i < varforms_.size(); ++i)
        {
            auto &varform = varforms_[i];
            auto &diff_cache = diff_caches_[i];
 
            Eigen::MatrixXd adjoint_p = get_adjoint_mat(*varform, *diff_cache, 0);
            Eigen::MatrixXd adjoint_nu = get_adjoint_mat(*varform, *diff_cache, 1);
            AdjointTools::dJ_initial_condition_adjoint_term(*varform, adjoint_nu, adjoint_p, cur_term);
 
            if (term.size() != cur_term.size())
            {
                term = cur_term;
            }
            else
            {
                term += cur_term;
            }
        }
 
        assert(term.size() == 2 * dof_num_);
 
        int active_num = active_dofs_.size();
        Eigen::VectorXd active_term(para_out_dof());
        for (int j = 0; j < active_num; ++j)
        {
            active_term(j) = term(active_dofs_(j));
            active_term(active_num + j) = term(dof_num_ + active_dofs_(j));
        }
 
        assert(active_term.size() == para_out_dof());
        return parametrization_.apply_jacobian(active_term, x);
    }
 
    int InitialConditionVariableToSimulation::inverse_dof() const
    {
        return parametrization_.inverse_size(para_out_dof());
    }
 
    Eigen::VectorXd InitialConditionVariableToSimulation::inverse_eval() const
    {
        assert(diff_caches_[0]->initial_condition_override && "Initial-condition optimization must initialize its override");
        const auto &initial_condition_override = *diff_caches_[0]->initial_condition_override;
        const Eigen::MatrixXd &sol = initial_condition_override.solution;
        const Eigen::MatrixXd &vel = initial_condition_override.velocity;
        assert(sol.rows() == dof_num_ && sol.cols() >= 1 && "Initial solution override must match the simulation DOFs");
        assert(vel.rows() == dof_num_ && vel.cols() >= 1 && "Initial velocity override must match the simulation DOFs");
 
        int active_num = active_dofs_.size();
        Eigen::VectorXd y(para_out_dof());
        for (int j = 0; j < active_num; ++j)
        {
            y(j) = sol(active_dofs_(j), 0);
            y(active_num + j) = vel(active_dofs_(j), 0);
        }
        return parametrization_.inverse_eval(y);
    }
 
    Eigen::VectorXd InitialConditionVariableToSimulation::apply_parametrization_jacobian(const Eigen::VectorXd &, const Eigen::VectorXd &) const
    {
        // Not implemented because there's no user
        log_and_throw_adjoint_error("apply_parametrization_jacobian is not implemented in {} variable to simulation.", name());
    }
 
    int InitialConditionVariableToSimulation::para_out_dof() const
    {
        return 2 * active_dofs_.size();
    }
 
} // namespace polyfem::solver