C++ (Cpp) NodeSet::both_edge_nodes示例

static void derivatives_at_mid_elem( NodeSet nodeset,
                                     size_t* vertices,
                                     MsqVector<2>* derivs,
                                     size_t& num_vtx )
{
    // fast linear case
    // This is provided as an optimization for linear elements.
    // If this block of code were removed, the general-case code
    // below should produce the same result.
  if (!nodeset.have_any_mid_node()) {
    num_vtx = 4;
    vertices[0] = 0; derivs[0][0] = -0.5; derivs[0][1] = -0.5;
    vertices[1] = 1; derivs[1][0] =  0.5; derivs[1][1] = -0.5;
    vertices[2] = 2; derivs[2][0] =  0.5; derivs[2][1] =  0.5;
    vertices[3] = 3; derivs[3][0] = -0.5; derivs[3][1] =  0.5;
    return;
  }
  
  num_vtx = 0;
  
    // N_0
  if (!nodeset.both_edge_nodes(0,3)) {  // if eiter adjacent mid-edge node is missing
    vertices[num_vtx] = 0;
    derivs[num_vtx][0] = nodeset.mid_edge_node(3) ? 0.0 : -0.5;
    derivs[num_vtx][1] = nodeset.mid_edge_node(0) ? 0.0 : -0.5;
    ++num_vtx;
  }
  
    // N_1
  if (!nodeset.both_edge_nodes(0,1)) {  // if eiter adjacent mid-edge node is missing
    vertices[num_vtx] = 1;
    derivs[num_vtx][0] = nodeset.mid_edge_node(1) ? 0.0 :  0.5;
    derivs[num_vtx][1] = nodeset.mid_edge_node(0) ? 0.0 : -0.5;
    ++num_vtx;
  }
  
    // N_2
  if (!nodeset.both_edge_nodes(1,2)) {  // if eiter adjacent mid-edge node is missing
    vertices[num_vtx] = 2;
    derivs[num_vtx][0] = nodeset.mid_edge_node(1) ? 0.0 :  0.5;
    derivs[num_vtx][1] = nodeset.mid_edge_node(2) ? 0.0 :  0.5;
    ++num_vtx;
  }
  
    // N_3
  if (!nodeset.both_edge_nodes(2,3)) {  // if eiter adjacent mid-edge node is missing
    vertices[num_vtx] = 3;
    derivs[num_vtx][0] = nodeset.mid_edge_node(3) ? 0.0 : -0.5;
    derivs[num_vtx][1] = nodeset.mid_edge_node(2) ? 0.0 :  0.5;
    ++num_vtx;
  }
  
    // N_4
  if (nodeset.mid_edge_node(0)) {
    vertices[num_vtx] = 4;
    derivs[num_vtx][0] =  0.0;
    derivs[num_vtx][1] = -1.0;
    ++num_vtx;
  }
  
    // N_5
  if (nodeset.mid_edge_node(1)) {
    vertices[num_vtx] = 5;
    derivs[num_vtx][0] =  1.0;
    derivs[num_vtx][1] =  0.0;
    ++num_vtx;
  }
  
    // N_6
  if (nodeset.mid_edge_node(2)) {
    vertices[num_vtx] = 6;
    derivs[num_vtx][0] =  0.0;
    derivs[num_vtx][1] =  1.0;
    ++num_vtx;
  }
  
    // N_7
  if (nodeset.mid_edge_node(3)) {
    vertices[num_vtx] = 7;
    derivs[num_vtx][0] = -1.0;
    derivs[num_vtx][1] =  0.0;
    ++num_vtx;
  }
  
    // N_8 (mid-quad node) never contributes to Jacobian at element center!!!
}