Changing the BEM++ options¶
BEM++ uses a global options structure in bempp.api.global_parameters to control
various aspects of the library. In addition several functions and classes have a
parameters attribute that can take a custom parameters object. This is useful
if for a certain function one wants to override the global parameters. To create
a custom parameters object juse use the command
parameters = bempp.api.common.global_parameters()
In the following we give a description of all global parameter options.
Description of all global parameters¶
bempp.api.global_parameters.assembly.boundary_operator_assembly_type: Controls wheter boundary operators are assembled in dense mode or in hmat mode. The default is hmat to use H-Matrix assembly for boundary operators.bempp.api.global_parameters.assembly.potential_operator_assembly_type: Controls wheter potential operators are assembled in dense mode or in hmat mode. The default is hmat to use H-Matrix assembly for potential operators. H-Matrix assembly for exterior potentials is almost always preferable.bempp.api.global_parameters.assembly.enable_singular_integral_caching: If set to True (default) singular integrals are pre-calculated and cached before the regular integrals are calculated. This usually gives a small speed advantage and should not need to be modified.bempp.api.global_parameters.assembly.enable_interpolation_for_oscillatory_kernels: If set to True (default) Helmholtz type kernels (including Maxwell) are evaluated using a piecewise Hermite interpolation. This is significantly faster than evaluating the exponentials directly.bempp.api.global_parameters.assembly.interpolation_points_per_wavelength: The number of interpolation points per wavelength to be used (default 5000).bempp.api.global_parameters.quadrature: Modify the quadrature options (see also Quadrature).bempp.api.global_parameters.hmat.admissibility: The type of admissibility condition. The default is weak, which declares a block cluster admissible if the column and range cluster bounding boxes do not intersect. The classical H-Matrix admissibility condition is obtained by setting this parameter to strong.bempp.api.global_parameters.hmat.coarsening:: If True (default) enable automatic coarsening of H-Matrices.bempp.api.global_parameters.hmat.coarsening_accuracy: The accuracy of the coarsening procedure. The default value is 0, meaning that the same accuracy eps as for the H-Matrix assembly is used.bempp.api.global_parameters.hmat.compression_algorithm: The compression algorithm that is used. The default is aca, which uses a modifed Adaptive Cross Approximation with heuristic failure detection. By choosing dense no compression is performed and all blocks are stored as dense matrices.bempp.api.global_parameters.hmat.eps: The relative accuracy of the H-Matrix compression.bempp.api.global_parameters.hmat.mat_vec_parallel_levels: The H-Matrix vector product is a hierarchic operation. For each node of the tree parallel tasks corresponding to the number of children are created. This parameter states at what level a serial algorithm should start to be used in order to create not too many very small tasks that can be inefficient (default 5).bempp.api.global_parameters.hmat.max_block_size. For load-balancing reasons it is useful to restrict the maximum block size as each block is compressed using a single task and a very large block would occupy a single task too long. The default is 2048, but should be increased for very large problems.bempp.api.global_parameters.hmat.max_rank. The maximum allowed rank for the compression of a block. The block compression stops at this rank even if the accuracy requirements are not yet achieved. The default is 30.bempp.api.global_parameters.hmat.min_block_size. A measure for the minimum size of a block. The default is 20, meaning that clustering stops if fewer than 20 degrees of freedom are left in a cluster node.