Just call it :))
You will need:
1. expm function declaration before the call. Note, Fortran passes all
arguments by their addresses, not values. So an integer parameter is
passed as int *, etc.
2. actual call to expm() in your code
3. link your code to lapack, for that add a flag to linker: -l lapack.
This is enough if Lapack is installed with standard paths.
But I do not see expm subroutine in lapack, is it there?
If it is not, you can find eigenvectors and eigenvalues as I have
already written before.
Ivan
On 23.03.2011 22:48, pleramorphyllactic wrote:
Apologies, mis-fire.
Anyway, So I can solve the system easily using matlab, etc. And so my
question is most clearly:
How do I compute the exponential of a matrix easily in deal.ii, with
the least amount of fuss (I can't find a function in the documentation
that does this)?
Or if that's too vague, ...
How do I go about using the expm subroutine from LAPACK in my deal.ii
code?
Many thanks,
Craig
On Wed, Mar 23, 2011 at 2:43 PM, pleramorphyllactic
<[email protected] <mailto:[email protected]>>
wrote:
Thanks guys,
I think my wording belies my understanding of the problem
somehow. I have a very large deal.ii code that solves a highly
nonlinear multicomponent PDE, and is working quite well. I do
know how to do what I need in matlab, and a number fo different
software. For example, I can exponentiate a matrix in LAPACK,
though have never h
My question is onl
On Wed, Mar 23, 2011 at 2:29 PM, Markus Bürg <[email protected]
<mailto:[email protected]>> wrote:
Hello Evan,
deal.II is a finite element library and does only support the
basic linear algebra operations for matrices. Perhabs you want
to use MATLAB or some other mathematics package, which already
has support for such stuff like matrix exponentials.
Best Regards,
Markus
Am 23.03.11 19:50, schrieb pleramorphyllactic:
Hi all,
Hope this isn't too simple of a question. I have a coupled
system of Linear ODEs, and want to solve in deal.ii. So,
say I have
x' = Ax,
where x is a state vector and A is a matrix. The simple way
(that occurs to me) is doing matrix exponentiation, so
finding: x = exp(At) * x_{0} . Is matrix exponentiation
supported? ... and/or if not, does anyone have an easy/fast
way you might approach this issue?
Thanks a ton,
Evan
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