Comparison of different approaches

Comparison of the error
(compared to very fine grid results;
the number after comma in the legend is N from the problem description)

Modifying:

• number of nodes
• degree of polynomial
  
• adding partial refinement

The refined domains look as follows
N=5



N=11

this one is refined 4 times, but the number of degrees of freedom is modified a little

For the points from the problem description the fine result is

• (0.25, 0.25) 0.03272
• (5/6, 1/6) 0.01840