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[Murtazo Nazarov <question103034@xxxxxxxxxxxxxxxxxxxxx>]

Question #103034 on DOLFIN changed:
https://answers.launchpad.net/dolfin/+question/103034

Murtazo Nazarov posted a new comment:
Murtazo Nazarov wrote:
> Your question #103034 on DOLFIN changed:
> https://answers.launchpad.net/dolfin/+question/103034
>
>     Status: Answered => Open
>
> You are still having a problem:
> Anders Logg wrote:
>   
>> Question #103034 on DOLFIN changed:
>> https://answers.launchpad.net/dolfin/+question/103034
>>
>>     Status: Open => Answered
>>
>> Anders Logg proposed the following answer:
>> On Wed, Mar 03, 2010 at 02:36:59AM -0000, Murtazo Nazarov wrote:
>>   
>>     
>>> New question #103034 on DOLFIN:
>>> https://answers.launchpad.net/dolfin/+question/103034
>>>
>>> Hi,
>>>
>>> I am wondering how to compute an L1-norm, and L_inf norm of a functional on the cell. For instance how to compute
>>>
>>> 1. ||\div(Pu)||_{L_\infty} ?
>>>     
>>>       
>> Try projecting div(Pu) onto piecewise constants and then pick the
>> largest absolute value in the vector.
>>
>>   
>>     
>
> I need L_inf norm on the cell. With this way, doesn't give the L_inf for 
> the entire domain?
>
> murtazo
>
>   

Instead of projecting div(Pu) onto piecewise constants, I projected it 
into dG(1), with this way I get three values on each cell, which I can 
then pick up the largest of them. That gives me then L_inf_K, where K is 
a cell. Now, I cannot figured out how is the numbering done for the 
dG(1) elements.

If N is a total number of cells, then my projected vector Pdg has 3*N 
elements. How can I pick up elements of Pdg in the cell K?

Thanks,
murtazo

>>> 2. ||\div(Pu)||_{L_1} ?
>>>     
>>>       
>> Try
>>
>> M = abs(div(Pu))*dx
>>
>> --
>> Anders
>>
>>
>>   
>>     
>>> where u is velocity (vector) and P is pressure (scalar). L2 norm is obvious to do.
>>>
>>> I use C++ interface
>>>
>>>     
>>>       
>>     
>
>

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