Improve efficiency of newton step conv check (#1775)

* improve efficiency of newton step conv check

* Update src/steadystateproblem.cpp

Co-authored-by: Daniel Weindl <[email protected]>

* fix test by increasing tolerance

Co-authored-by: Daniel Weindl <[email protected]>

Author: Fabian Fröhlich

include/amici/solver.h

@@ -897,7 +897,8 @@ class Solver {
     }
 
     /**
-     * @brief Returns how convergence checks for steadystate computation are performed.
+     * @brief Returns how convergence checks for steadystate computation are performed. If activated,
+     * convergence checks are limited to every 25 steps in the simulation solver to limit performance impact.
      * @return boolean flag indicating newton step (true) or the right hand side (false)
      */
     bool getNewtonStepSteadyStateCheck() const {

python/tests/test_preequilibration.py

@@ -338,6 +338,7 @@ def test_newton_solver_equilibration(preeq_fixture):
                 amici.SteadyStateSensitivityMode.newtonOnly]
 
     solver.setNewtonStepSteadyStateCheck(True)
+    solver.setRelativeToleranceSteadyState(1e-12)
 
     for equil_meth in settings:
         # set sensi method

src/steadystateproblem.cpp

@@ -630,7 +630,12 @@ void SteadystateProblem::runSteadystateSimulation(const Solver &solver,
     /* If run after Newton's method checks again if it converged */
     wrms_ = getWrms(model, sensitivityFlag);
     int sim_steps = 0;
-
+    
+    int convergence_check_frequency = 1;
+    
+    if (newton_step_conv_)
+        convergence_check_frequency = 25;
+        
     while (true) {
         /* One step of ODE integration
          reason for tout specification:
@@ -654,7 +659,8 @@ void SteadystateProblem::runSteadystateSimulation(const Solver &solver,
         /* getWrms needs to be called before getWrmsFSA such that the linear
          system is prepared for newton type convergence check */
         if (wrms_ < conv_thresh && check_sensi_conv_ &&
-            sensitivityFlag == SensitivityMethod::forward) {
+            sensitivityFlag == SensitivityMethod::forward &&
+            sim_steps % convergence_check_frequency == 0) {
             updateSensiSimulation(solver);
             wrms_ = getWrmsFSA(model);
         }