I need help on how to enforce box constraint and integral constraint on the solution when solving the variational problem. For example. let’s say I want to solve for “u” by \text{solve}(a == L, u , bc) where “u” satisfies the following constraints: a \leq u \leq b and \int_{\Omega} udx = C.
You can use the PETSc snes solver, https://bitbucket.org/fenics-project/dolfin/src/946dbd3e268dc20c64778eb5b734941ca5c343e5/python/demo/undocumented/contact-vi-snes/demo_contact-vi-snes.py?at=master#demo_contact-vi-snes.py-95 combined with a lagrange multiplier: https://fenicsproject.org/docs/dolfin/latest/python/demos/neumann-poisson/demo_neumann-poisson.py.html
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Thank you foe your reply. Can you please explain little bit about lengrange multiplier or post a fenixs link with lengrage multiplier? The two links posted above go to the same code?
That was a copy paste error. Link has been updated