On 5/21/21 1:52 PM, Shahin Heydari wrote:
m_i = sigma (m_ij) = int(phi_i dx)
Right. You compute the integral as a sum over the integrals on each cell. So
when you do
for (cell = ...)
for (i=...)
{
lump = 0;
for (q=...)
lump += ...
lump_cell_matrix(i,i) = lump;
}
then this is correct if you then add lump_cell_matrix(i,i) to your global
matrix.
You mention in your original question that you are unsure about what to do
with Q2 (or higher) elements. This is a difficult question, but there is a
good amount of literature on the topic. Just search for "mass lumping higher
order elements".
Best
W.
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