initial commit for workshop playground

Author: pancetta

pySDC/playgrounds/PinT_Workshop_2017/__init__.py

@@ -0,0 +1,99 @@
+import numpy as np
+
+from pySDC.implementations.problem_classes.HeatEquation_1D_FD_forced import heat1d_forced
+from pySDC.implementations.datatype_classes.mesh import mesh, rhs_imex_mesh
+from pySDC.implementations.collocation_classes.gauss_radau_right import CollGaussRadau_Right
+from pySDC.implementations.sweeper_classes.imex_1st_order import imex_1st_order
+from pySDC.implementations.transfer_classes.TransferMesh import mesh_to_mesh
+from pySDC.implementations.controller_classes.allinclusive_multigrid_nonMPI import allinclusive_multigrid_nonMPI
+
+from pySDC.helpers.stats_helper import filter_stats, sort_stats
+
+
+def main():
+    """
+    A simple test program to do PFASST runs for the heat equation
+    """
+
+    # initialize level parameters
+    level_params = dict()
+    level_params['restol'] = 1E-10
+    level_params['dt'] = 0.25
+
+    # initialize sweeper parameters
+    sweeper_params = dict()
+    sweeper_params['collocation_class'] = CollGaussRadau_Right
+    sweeper_params['num_nodes'] = 3
+    sweeper_params['QI'] = 'LU'  # For the IMEX sweeper, the LU-trick can be activated for the implicit part
+
+    # initialize problem parameters
+    problem_params = dict()
+    problem_params['nu'] = 0.1  # diffusion coefficient
+    problem_params['freq'] = 8  # frequency for the test value
+    problem_params['nvars'] = 511  # number of degrees of freedom for each level
+
+    # initialize step parameters
+    step_params = dict()
+    step_params['maxiter'] = 50
+
+    # initialize space transfer parameters
+    space_transfer_params = dict()
+    space_transfer_params['rorder'] = 2
+    space_transfer_params['iorder'] = 2
+
+    # initialize controller parameters
+    controller_params = dict()
+    controller_params['logger_level'] = 20
+
+    # fill description dictionary for easy step instantiation
+    description = dict()
+    description['problem_class'] = heat1d_forced                  # pass problem class
+    description['problem_params'] = problem_params                # pass problem parameters
+    description['dtype_u'] = mesh                                 # pass data type for u
+    description['dtype_f'] = rhs_imex_mesh                        # pass data type for f
+    description['sweeper_class'] = imex_1st_order                 # pass sweeper
+    description['sweeper_params'] = sweeper_params                # pass sweeper parameters
+    description['level_params'] = level_params                    # pass level parameters
+    description['step_params'] = step_params                      # pass step parameters
+    description['space_transfer_class'] = mesh_to_mesh            # pass spatial transfer class
+    description['space_transfer_params'] = space_transfer_params  # pass paramters for spatial transfer
+
+    # set time parameters
+    t0 = 0.0
+    Tend = 4.0
+
+    # instantiate controller
+    controller = allinclusive_multigrid_nonMPI(num_procs=16, controller_params=controller_params,
+                                               description=description)
+
+    # get initial values on finest level
+    P = controller.MS[0].levels[0].prob
+    uinit = P.u_exact(t0)
+
+    # call main function to get things done...
+    uend, stats = controller.run(u0=uinit, t0=t0, Tend=Tend)
+
+    # compute exact solution and compare
+    uex = P.u_exact(Tend)
+    err = abs(uex - uend)
+
+    print('\nError (vs. exact solution) at time %4.2f: %6.4e\n' % (Tend, err))
+
+    filtered_stats = filter_stats(stats, type='niter')
+
+    # convert filtered statistics to list of iterations count, sorted by process
+    iter_counts = sort_stats(filtered_stats, sortby='time')
+
+    # compute and print statistics
+    for item in iter_counts:
+        print('Number of iterations for time %4.2f: %2i' % item)
+
+    niters = np.array([item[1] for item in iter_counts])
+
+    print('   Mean number of iterations: %4.2f' % np.mean(niters))
+    print('   Range of values for number of iterations: %2i ' % np.ptp(niters))
+    print('   Position of max/min number of iterations: %2i -- %2i' % (int(np.argmax(niters)), int(np.argmin(niters))))
+
+
+if __name__ == "__main__":
+    main()