Cpp tutorial - GeoEnergyLab-EPFL/BigWham GitHub Wiki

Element Type

#include "core/elements/Triangle.h"
using Tri0 = bie::Triangle<0>;

Mesh

Mesh: getCollocationPoints, local to global and global to local transformation of traction and DD vectors

    #include "core/BEMesh.h"
    using Mesh = bie::BEMesh<Tri0>;
    
    // coord: coordinates
    // conn: connectivity matrix
    Mesh my_mesh(coord, conn);

Kernel

Each Kernel need to define the following virtual influence function of BIE_Kernel class

        // Source Element : source_elt
        // Reciever Element : source_elt
        // Source Collocation ID: i_s
        // Reciever Collocation ID: i_r
        virtual std::vector<double> influence(Es source_elt, il::int_t i_s,
                                                Er receiver_elt, il::int_t i_r) const;

For example

        #include "elasticity/3d/BIE_elastostatic_triangle_0_impls.h" // contains the defination of influence function
        #include "core/ElasticProperties.h"
        
        using MatProp = bie::ElasticProperties;
        
        // bie::ElasticKernelType : H or U or T or V
        using KernelH = bie::BIE_elastostatic<Tri0, Tri0, bie::ElasticKernelType::H>;
        
        MatProp elas(E, nu);
        // coord.size(1) : Dim of the kernel
        KernelH ker(elas, coord.size(1));

H-matrix construction

    
    #include "hmat/hmatrix/Hmat.h"
    #include "core/SquareMatrixGenerator.h"
    #include "core/hierarchical_representation.h"
    
    // Construct cluster and block cluster trees
    // max_leaf_size: size of cluster at the leaf level
    // admissibility criteria of block cluster tree
    bie::HRepresentation hr =
          bie::h_representation_square_matrix(my_mesh, max_leaf_size, eta);
    
    // Make MatrixGenerator: Link Kernel defination with H-matrix
    // Interface to tell H-mat which influence function to call 
    // Right now SquareMatrix Generator with same source and reciever element type is develped
    
    // ker: kernel object
    // my_mesh: mesh object
    
    using MatixGenerator = bie::SquareMatrixGenerator<double, Tri0, KernelH>;
    MatixGenerator M(my_mesh, ker, hr.permutation_0_);
    
    // Construct H-mat
    // eps_aca: Indirect way to give maximum rank of compression to ACA (approx SVD)
    bie::Hmat<double> h_(M, hr, eps_aca);

Mat vec operation

  // Mat vector operation using H-mat
    // dd: displacement discontunity vector at collocation points
    // trac: traction vector at collocation poitns
    // Right now dd and trac should be in local element coordinate system
    trac = h_.matvec(dd);