// Gmsh - Copyright (C) 1997-2025 C. Geuzaine, J.-F. Remacle
//
// See the LICENSE.txt file in the Gmsh root directory for license information.
// Please report all issues on https://gitlab.onelab.info/gmsh/gmsh/issues.
//
// Contributed by Amaury Johnen

#ifndef ORTHOGONAL_BASIS_H
#define ORTHOGONAL_BASIS_H

class FuncSpaceData;

class orthogonalBasis {
  // - Line: Legendre
  // - Quadrangle: Legendre x Legendre
  // - Triangle: Legendre x Jacobi
private:
  const int _type;
  const int _order;

public:
  orthogonalBasis();
  explicit orthogonalBasis(const FuncSpaceData &_data);
  orthogonalBasis(int type, int order) : _type(type), _order(order) {}
  ~orthogonalBasis() {}

  void f(double u, double v, double w, double *sf) const;
  void integralfSquared(double *val) const;
};

namespace LegendrePolynomials {
  void f(int n, double u, double *val);
  void fc(int n, double u, double *val);
  void df(int n, double u, double *val);
} // namespace LegendrePolynomials

namespace JacobiPolynomials {
  void f(int n, double alpha, double beta, double u, double *val);
  void df(int n, double alpha, double beta, double u, double *val);

  inline double Pochhammer(double x, int n)
  {
    double result = 1;
    for(int i = 0; i < n; i++) result *= x + i;
    return result;
  }
} // namespace JacobiPolynomials

#endif // GMSH_ORTHOGONALBASIS_H
