FEATool Multiphysics
v1.17.2
Finite Element Analysis Toolbox
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SF_DISC1 Linear discontinuous shape function (P1).
[ VBASE, NLDOF, XLDOF, SFUN ] = SF_DISC1( I_EVAL, N_SDIM, N_VERT, I_DOF, XI, AINVJAC, VBASE ) Evaluates discontinuous linear shape functions with with values defined by a constant and derivatives in the cell interior.
Input Value/[Size] Description ----------------------------------------------------------------------------------- i_eval scalar: 1 Evaluate function values >1 Evaluate values of derivatives n_sdim scalar: 1-3 Number of space dimensions n_vert scalar: 2-8 Number of vertices per cell i_dof scalar: 1-n_ldof Local basis function to evaluate xi [n_sdim(+1)] Local coordinates of evaluation point aInvJac [n,n_sdim(+1)*n_sdim] Inverse of transformation Jacobian vBase [n] Preallocated output vector . Output Value/[Size] Description ----------------------------------------------------------------------------------- vBase [n] Evaluated function values nLDof [4] Number of local degrees of freedom on vertices, edges, faces, and cell interiors xLDof [n_sdim,n_ldof] Local coordinates of local dofs sfun string Function name of called shape function
% Check for evaluation on simplicies. if( n_vert==n_sdim+1 ) f_simplex = 1; else f_simplex = 0; end nLDof = [0 0 0 n_sdim+1]; if( f_simplex ) xLDof = ones(n_sdim+1,1)/(n_sdim+1); else xLDof = zeros(n_sdim,1); end xLDof = repmat(xLDof,1,n_sdim+1); sfun = 'sf_disc1'; switch i_eval % Evaluation type flag. case {1} % Evaluation of function values. if ( f_simplex || i_dof<=n_sdim ) vBase = xi(i_dof); else vBase = 1; end case {2,3,4} % Evaluation of first order derivatives. if ( f_simplex || i_dof<=n_sdim ) i_col = i_dof+(i_eval-2)*(n_sdim+f_simplex); vBase = aInvJac(:,i_col); else vBase = 0; end otherwise vBase = 0; end