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Implement matrix assembly and factorization persistent through entire simulation #567

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3 changes: 2 additions & 1 deletion src/chrono/timestepper/ChTimestepperHHT.cpp
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Expand Up @@ -34,7 +34,8 @@ ChTimestepperHHT::ChTimestepperHHT(ChIntegrableIIorder* intgr)
h_min(1e-10),
h(1e6),
num_successful_steps(0),
modified_Newton(true) {
modified_Newton(true),
persistent_Newton(false) {
SetAlpha(-0.2); // default: some dissipation
}

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8 changes: 8 additions & 0 deletions src/chrono/timestepper/ChTimestepperHHT.h
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Expand Up @@ -77,6 +77,13 @@ class ChApi ChTimestepperHHT : public ChTimestepperIIorder, public ChImplicitIte
/// Default: true.
void SetModifiedNewton(bool enable) { modified_Newton = enable; }

/// Enable/disable persistent Newton.
/// If enabled, the Newton matrix is evaluated, assembled, and factorized only once
/// at the beginning of the first step or if the Newton iteration does not converge with an out-of-date matrix.
/// If disabled, the Newton matrix is evaluated at every iteration of the nonlinear solver.
/// Default: false.
void SetPersistentNewton(bool enable) { persistent_Newton = enable; }

/// Perform an integration timestep, by advancing the state by the specified time step.
virtual void Advance(const double dt) override;

Expand Down Expand Up @@ -126,6 +133,7 @@ class ChApi ChTimestepperHHT : public ChTimestepperIIorder, public ChImplicitIte
unsigned int num_successful_steps; ///< number of successful steps

bool modified_Newton; ///< use modified Newton?
bool persistent_Newton; ///< use persistent Newton?
bool matrix_is_current; ///< is the Newton matrix up-to-date?
bool call_setup; ///< should the solver's Setup function be called?

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