A_bed A_surface aspect_schoof B_bed B_schoof blatter_coarsening_hook blatter_restriction_hook C_bed C_surface compute_2D_principal_strain_rates compute_2D_stresses copy_staggered_vec create D2 disable_ew enable_ew H0_schoof H_exact ISMIPHOMTest L_schoof m_schoof set_diagonal_matrix_entry SSAFactory SSAFD_RegionalFactory SSAFDFactory SSAFEMFactory u_exact u_exterior weight weight zero_above_ice

compute_2D_principal_strain_rates() void pism::stressbalance::compute_2D_principal_strain_rates ( const array::Vector1 &  V, const array::CellType1 &  mask, array::Array2D< PrincipalStrainRates > &  result  ) Compute eigenvalues of the horizontal, vertically-integrated strain rate tensor. Calculates all components \(D_{xx}, D_{yy}, D_{xy}=D_{yx}\) of the vertically-averaged strain rate tensor \(D\) [SchoofStream]. Then computes the eigenvalues result(i,j,0) = (maximum eigenvalue), result(i,j,1) = (minimum eigenvalue). Uses the provided thickness to make decisions (PIK) about computing strain rates near calving front. Note that result(i,j,0) >= result(i,j,1), but there is no necessary relation between the magnitudes, and either principal strain rate could be negative or positive. Result can be used in a calving law, for example in eigencalving (PIK). Note: strain rates will be derived from SSA velocities, using ghosts when necessary. Both implementations (SSAFD and SSAFEM) call update_ghosts() to ensure that ghost values are up to date. Definition at line 682 of file StressBalance.cc. References pism::East, pism::array::Array::grid(), pism::array::CellType::ice_free(), pism::mask::ice_free(), pism::North, pism::South, pism::array::Array2D< T >::star(), and pism::West. Referenced by pism::stressbalance::PSB_strain_rates::compute_impl(), pism::calving::EigenCalving::update(), pism::calving::vonMisesCalving::update(), and pism::FractureDensity::update().