Yep, that's right, use the RB method to solve for u'.

Note that you put a(u0,v) on the right-hand side, since u0 is known 
(it's the "lifting function").

David



On 01/24/2013 11:34 PM, Kyunghoon Lee wrote:
> Thanks for clearing it up.  Then I guess we just solve for u'
>
> a(u',v) + a(u0,v) = f(v)
>
> and attach assemblies a(u',v), a(u0,v), and f(v) as usual, then restore u
> by u = u' + u0.
>
> K. Lee.
>
> On Fri, Jan 25, 2013 at 12:17 PM, David Knezevic <[email protected]
>> wrote:
>> Hi K,
>>
>> heterogeneously_constrain_element_matrix_and_vector is not relevant to
>> Reduced Basis stuff. For Reduced Basis formulations, you have to
>> transform the problem using a lifting function so that it has zero
>> Dirichlet BC's --- this is essential since you want your Reduced Basis
>> space to be a vector space, i.e. it must contain 0 (which would be not
>> be the case with non-zero Dirichlet BCs). This lifting function approach
>> is what you described in your email already, so that's fine.
>>
>> Once you've transformed your problem using a lifting function, then you
>> just proceed as normal, e.g. as in reduced_basis_ex1. The only trick is
>> you have to add your lifting function back on at the end to recover u
>> from u'.
>>
>> David
>>
>>
>>
>> On 01/24/2013 11:10 PM, Kyunghoon Lee wrote:
>>> Hi all,
>>>
>>> In my previous email regarding inhomogeneous Dirichlet boundary
>> conditions,
>>> David suggested using heterogenously_constrain_element_matrix_and_vector
>> in
>>> introduction_ex4, but I'm not sure of how to deal with inhomogeneous
>>> Dirichlet BCs in connection with reduced basis models.  Suppose we have a
>>> simple steady state heat conduction model whose BCs are u = T on \Gamma
>> and
>>> u = 0 on the rest surfaces.  After variable change, we solve
>>>
>>> a(u',v) = f(v) - a(u0,v)
>>>
>>> where 1) u' = u - T on \Gamma and u' = u on the rest surfaces; and 2) u0
>> =
>>> T on \Gamma and u0 = zero on the rest surfaces.  I thought we build the
>> LHS
>>> then call attach_F_assembly to attach it, but in that case, I'm not sure
>>> how heterogenously_constrain_element_matrix_and_vector can be used.  Or
>>> should we attach a(u',v) and f(v) as usual then call
>>> heterogenously_constrain_element_matrix_and_vector to impose - a(u0,v) on
>>> the LHS?  I'd appreciate if someone can briefly describe how the function
>>> work.
>>>
>>> Regards,
>>> K. Lee.
>>>
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