Ok - I just committed a set of changes that adds capability for computing
discrete norms of NumericVectors for the entries corresponding to a
variable's dofs.
To do this I added 3 new public methods to NumericVector:
subset_l2_norm()
subset_l1_norm()
subset_linfty_norm()
They each take a std::set corresponding to the entries to take the norm on.
I actually implemented these functions in the base class... but I did leave
them virtual in case someone wants to write optimized versions of these for
the leaf classes.
I also modified (and added a couple of private methods)
System::calculate_norm() methods.
I'm not wedded to these names... please feel free to rename them.
If you see anything wonky in the new code feel free to tear me a new one
about it. ;-)
Derek
On Wed, Nov 5, 2008 at 5:27 PM, Derek Gaston <[EMAIL PROTECTED]> wrote:
> So... after hashing this out with some people around here... I'm now
> thinking that the vector multiply and call linear algebra package norm is a
> bad idea. Firstly, we have some systems where we're solving up to 9
> variables! That means we'd have to do all of that stuff every time.... not
> too mention wasting memory with all of the zeroes hanging around in that
> vector....
>
> I'm thinking now of a NumericVector::subset_norm() that takes a std::set of
> the local dof indices to perform the norm on and a norm type (or we could
> make separate norm functions... either way).
>
> The std::set could easily be created in System::calculate_norm() for each
> variable that you want the discrete norm for and then call subset_norm() the
> appropriate number of times.
>
> And here's where it gets nutty: we just do our own damn norm calculation.
> It's not like it's rocket science. We do it right in NumericVector using
> the interface functions (like operator() ) so that every NumericVector gets
> this capability.
>
> What do you think?
>
> Derek
>
>
>
> On Nov 5, 2008, at 5:03 PM, Roy Stogner wrote:
>
>
>>
>> On Wed, 5 Nov 2008, Kirk, Benjamin (JSC-EG) wrote:
>>
>> Could the api allow you to specify the indices from user-space? The
>>> reason I ask is because if all your variables are the same type it
>>> is pretty easy to figure out the range from the first_local_index,
>>> last_local_index, n_vars, and var_num.
>>>
>>> That's a little hackish to do inside the library...
>>>
>>
>> A *little* hackish? No, requiring the command line option
>> "--node_major_dofs" to use that coefficient numbering, that was a
>> little hackish. *Breaking* that option (as well as Taylor-Hood
>> elements, etc.) would be a *lot* hackish. ;-)
>>
>> But as an optimization which could fall back on my more general code,
>> it's a very good idea. Use NumericVector::subrange_norm() only if
>> we're using var-major numbering, and have the DofMap cache the
>> first_local_index_var[n] for each variable so we get the range limits
>> right even if there's differing FE types in use.
>> ---
>> Roy
>>
>
>
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