[petsc-dev] I think equispaced nodes are in the wrong place

[Matthew Knepley]

Try running this:

make -f ./gmakefile test search="snes_tutorials-ex13_2d_p1_conv"
EXTRA_OPTIONS="-potential_petscspace_degree 3
-potential_petscdualspace_lagrange_node_type equispaced -petscds_view
::ascii_info_detail"

You see that

# >           Dual basis vector 0
# >               Quadrature on a unknown of order -1 on 1 points (dim 2)
# >               p0 (-0.333333, -0.333333) +1
# >           Dual basis vector 1
# >               Quadrature on a unknown of order -1 on 1 points (dim 2)
# >               p0 (-0.25, -1) +1
# >           Dual basis vector 2
# >               Quadrature on a unknown of order -1 on 1 points (dim 2)
# >               p0 (+0.25, -1) +1
# >           Dual basis vector 3
# >               Quadrature on a unknown of order -1 on 1 points (dim 2)
# >               p0 (+0.25, -0.25) +1
# >           Dual basis vector 4
# >               Quadrature on a unknown of order -1 on 1 points (dim 2)
# >               p0 (-0.25, +0.25) +1
# >           Dual basis vector 5
# >               Quadrature on a unknown of order -1 on 1 points (dim 2)
# >               p0 (-1, +0.25) +1
# >           Dual basis vector 6
# >               Quadrature on a unknown of order -1 on 1 points (dim 2)
# >               p0 (-1, -0.25) +1
# >           Dual basis vector 7
# >               Quadrature on a unknown of order -1 on 1 points (dim 2)
# >               p0 (-1, -1) +1
# >           Dual basis vector 8
# >               Quadrature on a unknown of order -1 on 1 points (dim 2)
# >               p0 (+1, -1) +1
# >           Dual basis vector 9
# >               Quadrature on a unknown of order -1 on 1 points (dim 2)
# >               p0 (-1, +1) +1

but I think those should be +- 1/3, not 1/4. What is going on?

  Thanks,

     Matt
-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

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