[ADOL-C] Activate/deactivate adoubles
andreas.puettmann at rwth-aachen.de
Sat Jun 19 07:20:35 EDT 2010
I want to use ADOL-C to compute PDE solution sensitivities w.r.t. a
bunch of model parameters. Altogether, we are talking here about a
number of approximately 20 parameters. However, in one single run of my
solver, the user is usually not interested in partial derivatives w.r.t.
all of these 20 parameters, but only say 5 of them (arbitrarily chosen
from the whole set).
I already integrated the ADOL-C tapeless mode into my code, and it works
fine. I made all of my model parameters adoubles, thus being able to
activate derivative computation w.r.t. a specific parameter by just
setting its ADValue to 1, or otherwise leaving at 0. This approach is
probably not really high-performance because in any case all parameters
are in fact active although most of them may have a 0 ADValue. Anyway,
it works and so far I am fine with it.
However, now I want to change to taping mode to be able to use the
drivers for Hessian matrices etc. What would be the best way to realize
I definitely want to keep all of my parameters as adoubles because the
user should potentially be able to compute derivates w.r.t. all of them
at the same time, although this will usually not be the case. I fear
that especially the computation of second order derivatives will be
significantly slower if all parameters are active, although only
derivatives w.r.t. a few parameters are desired.
Is there a means to activate and deactive adoubles? In my case, it would
be perfect if I could make ADOL-C treat some (in fact most) of the
adoubles just like regular doubles.
Thanks for any help!
More information about the ADOL-C