[Getdp] Characteristic function

sdurand sdurand at cage.ugent.be
Wed Jun 17 17:21:34 CEST 2009

Hello everybody,

I want to solve a 2D optimization problem in GetDP where the cost
functional is an integral over an inner domain (eg circle). Therefore, I
obtain an adjoint problem in which the right hand side is an integral
over this domain. Since this domain has the same material parameters as
its surroundings, I didn't define it as a separate region.

To calculate the integral over this domain, I have defined the
characteristic function as

Ie [domain] = ($X^2 + $Y^2 <= 4.) ? 1. : 0.;

such that the right hand side of my problem becomes

 Galerkin { [ Ie[]*({u}-{ud}), {p} ]; In domain;
	Jacobian Vol; Integration GradGrad; }

where u and ud are results from other calculations.

However, I always get the "Null right hand side"-error. Is it not
allowed in GetDP to use characteristic functions instead of Physical
Regions for integration?

Thank you,

Stephane Durand
Department of Mathematical analysis
Research group of Numerical Functional Analysis and Mathematical
Ghent University

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