TEST(NumLib, TimeSteppingIterationNumberBased1)
{
std::vector<std::size_t> iter_times_vector = {0, 3, 5, 7};
std::vector<double> multiplier_vector = {2.0, 1.0, 0.5, 0.25};
NumLib::IterationNumberBasedAdaptiveTimeStepping alg(1, 31, 1, 10, 1, iter_times_vector, multiplier_vector);
ASSERT_TRUE(alg.next()); // t=2, dt=1
NumLib::TimeStep ts = alg.getTimeStep();
ASSERT_EQ(1u, ts.steps());
ASSERT_EQ(1., ts.previous());
ASSERT_EQ(2., ts.current());
ASSERT_EQ(1., ts.dt());
ASSERT_TRUE(alg.accepted());
ASSERT_TRUE(alg.next()); // t=4, dt=2
// dt*=2
alg.setNIterations(3);
ASSERT_TRUE(alg.next()); // t=8, dt=4
ts = alg.getTimeStep();
ASSERT_EQ(3u, ts.steps());
ASSERT_EQ(4., ts.previous());
ASSERT_EQ(8., ts.current());
ASSERT_EQ(4., ts.dt());
ASSERT_TRUE(alg.accepted());
// dt*=1
alg.setNIterations(5);
ASSERT_TRUE(alg.next()); // t=12, dt=4
ts = alg.getTimeStep();
ASSERT_EQ(4u, ts.steps());
ASSERT_EQ(8., ts.previous());
ASSERT_EQ(12., ts.current());
ASSERT_EQ(4., ts.dt());
ASSERT_TRUE(alg.accepted());
// dt*=0.5
alg.setNIterations(7);
ASSERT_TRUE(alg.next()); // t=14, dt=2
ts = alg.getTimeStep();
ASSERT_EQ(5u, ts.steps());
ASSERT_EQ(12., ts.previous());
ASSERT_EQ(14., ts.current());
ASSERT_EQ(2., ts.dt());
ASSERT_TRUE(alg.accepted());
// dt*=0.25 but dt_min = 1
alg.setNIterations(8); // exceed max
ASSERT_TRUE(alg.next()); // t=13, dt=1
ts = alg.getTimeStep();
ASSERT_EQ(5u, ts.steps());
ASSERT_EQ(12., ts.previous());
ASSERT_EQ(13, ts.current());
ASSERT_EQ(1., ts.dt());
ASSERT_FALSE(alg.accepted());
// restart, dt*=1
alg.setNIterations(4);
ASSERT_TRUE(alg.next()); // t=14, dt=1
ts = alg.getTimeStep();
ASSERT_EQ(6u, ts.steps());
ASSERT_EQ(13., ts.previous());
ASSERT_EQ(14, ts.current());
ASSERT_EQ(1., ts.dt());
ASSERT_TRUE(alg.accepted());
}
TEST(NumLibTimeStepping, testEvolutionaryPIDcontroller)
{
const char xml[] =
"<time_stepping>"
" <type>EvolutionaryPIDcontroller</type>"
" <t_initial> 0.0 </t_initial>"
" <t_end> 10 </t_end>"
" <dt_guess> 0.01 </dt_guess>"
" <dt_min> 0.001 </dt_min>"
" <dt_max> 1 </dt_max>"
" <rel_dt_min> 0.01 </rel_dt_min>"
" <rel_dt_max> 5 </rel_dt_max>"
" <tol> 1.e-3 </tol>"
"</time_stepping>";
auto const PIDStepper = createTestTimeStepper(xml);
double solution_error = 0.;
int const number_iterations = 0;
// 1st step
ASSERT_TRUE(PIDStepper->next(solution_error, number_iterations));
NumLib::TimeStep ts = PIDStepper->getTimeStep();
double h_new = 0.01;
double t_previous = 0.;
ASSERT_EQ(1u, ts.steps());
ASSERT_EQ(t_previous, ts.previous());
ASSERT_EQ(t_previous + h_new, ts.current());
ASSERT_EQ(h_new, ts.dt());
ASSERT_TRUE(PIDStepper->accepted());
t_previous += h_new;
// e_n_minus1 is filled.
solution_error = 1.0e-4;
PIDStepper->next(solution_error, number_iterations);
ts = PIDStepper->getTimeStep();
h_new = ts.dt();
ASSERT_EQ(2u, ts.steps());
const double tol = 1.e-16;
ASSERT_NEAR(t_previous, ts.previous(), tol);
ASSERT_NEAR(t_previous + h_new, ts.current(), tol);
ASSERT_TRUE(PIDStepper->accepted());
t_previous += h_new;
// e_n_minus2 is filled.
solution_error = 0.5e-3;
PIDStepper->next(solution_error, number_iterations);
ts = PIDStepper->getTimeStep();
h_new = ts.dt();
ASSERT_EQ(3u, ts.steps());
ASSERT_NEAR(t_previous, ts.previous(), tol);
ASSERT_NEAR(t_previous + h_new, ts.current(), tol);
ASSERT_TRUE(PIDStepper->accepted());
// error > TOL=1.3-3, step rejected and new step size estimated.
solution_error = 0.01;
PIDStepper->next(solution_error, number_iterations);
ts = PIDStepper->getTimeStep();
h_new = ts.dt();
// No change in ts.steps
ASSERT_EQ(3u, ts.steps());
// No change in ts.previous(), which is the same as that of the previous
// step.
ASSERT_NEAR(t_previous, ts.previous(), tol);
ASSERT_NEAR(t_previous + h_new, ts.current(), tol);
ASSERT_FALSE(PIDStepper->accepted());
t_previous += h_new;
// With e_n, e_n_minus1, e_n_minus2
solution_error = 0.4e-3;
PIDStepper->next(solution_error, number_iterations);
ts = PIDStepper->getTimeStep();
h_new = ts.dt();
ASSERT_EQ(4u, ts.steps());
ASSERT_NEAR(t_previous, ts.previous(), tol);
ASSERT_NEAR(t_previous + h_new, ts.current(), tol);
ASSERT_TRUE(PIDStepper->accepted());
}