reorganized project for cleaner filesystem

nufi/fields.h

@@ -0,0 +1,168 @@
+#ifndef FIELDS_H
+#define FIELDS_H
+
+#include <cmath>
+#include <deal.II/base/function.h>
+#include "nufi/parameters.h"
+#include "nufi/splines.h"
+#include "nufi/lsmr.h"
+
+using namespace dealii;
+
+inline double f0(const double x,
+                 const double v,
+                 const double eps = Parameters::EPS,
+                 const double k   = Parameters::WAVE_NR)
+{
+  const double prefactor = Parameters::F0_FACTOR * (1.0 + eps * std::cos(k*x));
+  const double gaussian  = v*v  * std::exp(-0.5 * v*v);
+
+  return prefactor * gaussian;
+}
+
+
+inline double compute_rho(const double x,
+                          const unsigned int Nv = Parameters::NV)
+{
+  const double dv = (Parameters::V_DOMAIN_RIGHT - Parameters::V_DOMAIN_LEFT) / Nv;
+
+  double integral = 0.0;
+
+  for (unsigned int i = 0; i < Nv; ++i)
+  {
+    const double v = Parameters::V_DOMAIN_LEFT + (i + 0.5) * dv;
+    integral += f0(x, v) * dv;
+  }
+
+  return 1.0 - integral;
+}
+
+
+template <size_t dx = 0>
+double eval(double x, const double *coeffs) noexcept
+{
+    using std::floor;
+
+    // Shift to a box that starts at 0.
+    x -= Parameters::X_DOMAIN_LEFT;
+
+    // Get "periodic position" in box at origin.
+    x = x - Parameters::LX * floor( x/Parameters::LX ); 
+
+    // Knot number
+    double x_knot = floor( x/Parameters::SPLINE_DX); 
+
+    size_t ii = static_cast<size_t>(x_knot);
+
+    // Convert x to reference coordinates.
+    x = x/Parameters::SPLINE_DX - x_knot;
+
+    // Scale according to derivative.
+    double factor = 1;
+    for ( size_t i = 0; i < dx; ++i ) factor *= 1/Parameters::SPLINE_DX;
+
+    return factor*splines1d::eval<double,Parameters::SPLINE_ORDER,dx>(x, coeffs + ii);
+}
+
+template <typename real, size_t order>
+void interpolate( real *coeffs, const real *values) // Least Squares needs to be made
+{
+    std::unique_ptr<real[]> tmp { new real[ Parameters::SPLINE_NX ] };
+
+    for ( size_t i = 0; i < Parameters::SPLINE_NX; ++i )
+        tmp[ i ] = coeffs[ i ];
+
+    struct mat_t // STRUCT AND CONFIG NEEDS TO BE REVIEWED 
+    {
+        real  N[ order ];
+
+        mat_t()
+        {
+            splines1d::N<real,order>(0,N);
+        }
+
+        void operator()( const real *in, real *out ) const
+        {
+            for ( size_t i = 0; i < Parameters::SPLINE_NX; ++i )
+            {
+                real result = 0;
+                if ( i + order <= Parameters::SPLINE_NX )
+                {
+                    for ( size_t ii = 0; ii < order; ++ii )
+                        result += N[ii] * in[ i + ii ];
+                }
+                else
+                {
+                    for ( size_t ii = 0; ii < order; ++ii )
+                        result += N[ii]*in[ (i+ii) % Parameters::SPLINE_NX];
+                }
+                out[ i ] = result;
+            }
+        }
+    };
+
+    struct transposed_mat_t // STRUCT AND CONFIG NEEDS TO BE REVIEWED 
+    {
+        real  N[ order ];
+
+        transposed_mat_t()
+        {
+            splines1d::N<real,order>(0,N);
+        }
+
+        void operator()( const real *in, real *out ) const
+        {
+            for ( size_t i = 0; i < Parameters::SPLINE_NX; ++i )
+                out[ i ] = 0;
+
+            for ( size_t i = 0; i < Parameters::SPLINE_NX; ++i )
+            {
+                if ( i + order <= Parameters::SPLINE_NX )
+                {
+                    for ( size_t ii = 0; ii < order; ++ii )
+                        out[ i + ii ]  += N[ii] * in[ i ];
+                }
+                else
+                {
+                    for ( size_t ii = 0; ii < order; ++ii )
+                        out[ (i+ii) % Parameters::SPLINE_NX ] += N[ii]*in[ i ];
+                }
+            }
+        }
+    };
+
+    mat_t M; transposed_mat_t Mt;
+    lsmr_options<real> opt; opt.silent = true;
+    lsmr( Parameters::SPLINE_NX, Parameters::SPLINE_NX , M, Mt, values, tmp.get(), opt );
+
+    if ( opt.iter == opt.max_iter )
+        std::cerr << "Warning. LSMR did not converge.\n";
+
+    for ( size_t i = 0; i < Parameters::SPLINE_NX + order - 1; ++i )
+        coeffs[ i ] = tmp[ i % Parameters::SPLINE_NX ];
+}
+
+
+template <int dim>
+class ChargeDensity : public Function<dim> // only uses f0
+{
+public:
+  ChargeDensity(double eps,
+                double k,
+                unsigned int Nv)
+    : Function<dim>(1), eps(eps), k(k), Nv(Nv) {}
+
+  virtual double value(const Point<dim> &p,
+                       [[maybe_unused]] const unsigned int component = 0) const override
+  {
+    return compute_rho(p[0], Nv);
+  }
+
+private:
+  const double eps;
+  const double k;
+  const unsigned int Nv;
+};
+
+
+#endif