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// ---------------------------------------------------------------------
//
// Copyright (C) 2016 - 2017 by the deal.II authors
//
// This file is part of the deal.II library.
//
// The deal.II library is free software; you can use it, redistribute
// it, and/or modify it under the terms of the GNU Lesser General
// Public License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
// The full text of the license can be found in the file LICENSE at
// the top level of the deal.II distribution.
//
// ---------------------------------------------------------------------
#include <deal.II/base/point.h>
#include <deal.II/base/function_cspline.h>
#ifdef DEAL_II_WITH_GSL
#include <cmath>
#include <algorithm>
DEAL_II_NAMESPACE_OPEN
namespace Functions
{
template <int dim>
CSpline<dim>::CSpline(const std::vector<double> &x_,
const std::vector<double> &y_)
:
interpolation_points(x_),
interpolation_values(y_)
{
Assert (interpolation_points.size() > 0,
ExcCSplineEmpty(interpolation_points.size()));
Assert (interpolation_points.size() == interpolation_values.size(),
ExcCSplineSizeMismatch(interpolation_points.size(),interpolation_values.size()));
// check that input vector @p interpolation_points is provided in ascending order:
for (unsigned int i = 0; i < interpolation_points.size()-1; i++)
AssertThrow(interpolation_points[i]<interpolation_points[i+1],
ExcCSplineOrder(i,interpolation_points[i],interpolation_points[i+1]));
acc = gsl_interp_accel_alloc ();
const unsigned int n = interpolation_points.size();
cspline = gsl_spline_alloc (gsl_interp_cspline, n);
// gsl_spline_init returns something but it seems nobody knows what
gsl_spline_init (cspline, interpolation_points.data(), interpolation_values.data(), n);
}
template <int dim>
CSpline<dim>::~CSpline()
{
gsl_interp_accel_free (acc);
gsl_spline_free (cspline);
acc = nullptr;
cspline = nullptr;
}
template <int dim>
double
CSpline<dim>::value (const Point<dim> &p,
const unsigned int) const
{
// GSL functions may modify gsl_interp_accel *acc object (last argument).
// This can only work in multithreaded applications if we lock the data
// structures via a mutex.
Threads::Mutex::ScopedLock lock (acc_mutex);
const double &x = p[0];
Assert (x >= interpolation_points.front() && x <= interpolation_points.back(),
ExcCSplineRange(x,interpolation_points.front(),interpolation_points.back()));
return gsl_spline_eval (cspline, x, acc);
}
template <int dim>
Tensor<1,dim>
CSpline<dim>::gradient (const Point<dim> &p,
const unsigned int) const
{
// GSL functions may modify gsl_interp_accel *acc object (last argument).
// This can only work in multithreaded applications if we lock the data
// structures via a mutex.
Threads::Mutex::ScopedLock lock (acc_mutex);
const double &x = p[0];
Assert (x >= interpolation_points.front() && x <= interpolation_points.back(),
ExcCSplineRange(x,interpolation_points.front(),interpolation_points.back()));
const double deriv = gsl_spline_eval_deriv (cspline, x, acc);
Tensor<1,dim> res;
res[0] = deriv;
return res;
}
template <int dim>
double
CSpline<dim>::laplacian (const Point<dim> &p,
const unsigned int) const
{
// GSL functions may modify gsl_interp_accel *acc object (last argument).
// This can only work in multithreaded applications if we lock the data
// structures via a mutex.
Threads::Mutex::ScopedLock lock (acc_mutex);
const double &x = p[0];
Assert (x >= interpolation_points.front() && x <= interpolation_points.back(),
ExcCSplineRange(x,interpolation_points.front(),interpolation_points.back()));
return gsl_spline_eval_deriv2 (cspline, x, acc);
}
template <int dim>
SymmetricTensor<2,dim>
CSpline<dim>::hessian (const Point<dim> &p,
const unsigned int) const
{
SymmetricTensor<2,dim> res;
res[0][0] = laplacian(p);
return res;
}
template <int dim>
std::size_t
CSpline<dim>::memory_consumption () const
{
// only simple data elements, so
// use sizeof operator
return sizeof (*this) + 2*sizeof(double)*interpolation_values.size();
}
// explicit instantiations
template class CSpline<1>;
}
DEAL_II_NAMESPACE_CLOSE
#endif
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