07-Jan-2022 20:00:25 fem2d_bvp_linear_test(): MATLAB/Octave version 9.8.0.1380330 (R2020a) Update 2 Test fem2d_bvp_linear(). FEM2D_BVP_LINEAR_TEST01 Solve - del ( A del U ) + C U = F on the unit square with zero boundary conditions. A1(X,Y) = 1.0 C1(X,Y) = 0.0 F1(X,Y) = 2*X*(1-X)+2*Y*(1-Y). U1(X,Y) = X * ( 1 - X ) * Y * ( 1 - Y ) The grid uses 3 by 3 nodes. I J X Y U Uexact Error 1 1 0.000000 0.000000 0.000000 0.000000 0.000000e+00 2 1 0.500000 0.000000 0.000000 0.000000 0.000000e+00 3 1 1.000000 0.000000 0.000000 0.000000 0.000000e+00 1 2 0.000000 0.500000 0.000000 0.000000 0.000000e+00 2 2 0.500000 0.500000 0.078125 0.062500 1.562500e-02 3 2 1.000000 0.500000 0.000000 0.000000 0.000000e+00 1 3 0.000000 1.000000 0.000000 0.000000 0.000000e+00 2 3 0.500000 1.000000 0.000000 0.000000 0.000000e+00 3 3 1.000000 1.000000 0.000000 0.000000 0.000000e+00 l1 error = 0.00173611 L2 error = 0.00968806 H1S error = 0.0771115 fem2d_bvp_linear_test(): Normal end of execution. 07-Jan-2022 20:00:25