/usr/include/dune/localfunctions/dualmortarbasis/dualp1/dualp1localinterpolation.hh is in libdune-localfunctions-dev 2.3.1-1.
This file is owned by root:root, with mode 0o644.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 | // -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
#ifndef DUNE_DUAL_P1_LOCALINTERPOLATION_HH
#define DUNE_DUAL_P1_LOCALINTERPOLATION_HH
#include <vector>
namespace Dune
{
template<int dim, class LB>
class DualP1LocalInterpolation
{
public:
//! \brief Local interpolation of a function
template<typename F, typename C>
void interpolate (const F& f, std::vector<C>& out) const
{
typename LB::Traits::RangeType y;
typename LB::Traits::DomainType x;
// compute P1 interpolation coefficients
std::vector<C> p1Interpolation(dim+1);
// vertex 0
for (int i=0; i<dim; i++)
x[i] = 0;
f.evaluate(x,y); p1Interpolation[0] = y;
// remaining vertices
for (int i=0; i<dim; i++) {
for (int j=0; j<dim; j++)
x[j] = (i==j);
f.evaluate(x,y); p1Interpolation[i+1] = y;
}
// compute dual coefficients from the Lagrange ones
out.resize(dim+1);
for (int i=0; i<dim+1; i++) {
out[i] = 2*p1Interpolation[i]/(dim+2) ;
for (int j=0; j<i; j++)
out[i] += p1Interpolation[j]/(dim+2);
for (int j=i+1; j<=dim; j++)
out[i] += p1Interpolation[j]/(dim+2);
}
}
};
}
#endif
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