Residual for Stokes equation not equal to zero

3

I’m not convinced you’re computing the residual. Cf.

# Print residual
r = assemble(a(u, p, v, q) - L(v, q))
for bc in boundaries:
    bc.apply(r, w.vector())
print(r.norm("l2"))

>>> 9.950073998023825e-14
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