HiReconstruction.hpp

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/*! \file HiReconstruction.hpp
 * This class implements a high order surface/curve reconstruction method which takes a
 * surface/curve mesh as input and compute local polynomial fittings (in monomial basis) around user
 * specified vertices. Little noise is allowed and least square will be used in such case. This
 * method assumes the underlying geometry of input mesh is smooth. The local fitting results could
 * be used for estimate the exact geometry of the surface. For instance, if mesh refinement is
 * perform on the input mesh, then the position of new vertices introduced by refinement could be
 * estimated by the local fitting, rather than using linear interpolation.
 * Implementations are based on the WALF method in paper:
 * Jiao, Xiangmin, and Duo Wang. "Reconstructing high-order surfaces for meshing." Engineering with
 * Computers 28.4 (2012): 361-373.
 */

#ifndef HI_RECONSTRUCTION_HPP
#define HI_RECONSTRUCTION_HPP

#include "moab/Range.hpp"
#include "moab/HalfFacetRep.hpp"

#ifdef MOAB_HAVE_MPI
#include "moab/ParallelComm.hpp"
#endif

#include <vector>

namespace moab
{
enum GEOMTYPE
{
    HISURFACE,
    HI3DCURVE,
    HI2DCURVE
};

class Core;
class HalfFaceRep;
class ParallelComm;

class HiReconstruction
{
  public:
    HiReconstruction( Core* impl,
                      ParallelComm* comm  = 0,
                      EntityHandle meshIn = 0,
                      int minpnts         = 5,
                      bool recwhole       = true );

    ~HiReconstruction();

    ErrorCode initialize( bool recwhole );

    //! \brief Reconstruct a high order surface on given surface mesh
    /** Given a mesh, compute vertex based polynomial fittings for all vertices hosted by current
     * processor. The result will be stored interally for later usage of evalution. The inputs are:
     * a) degree, which is the order of polynomial used for vertex based fitting. b) interp, if it's
     * true, then interpolation will be applied for local fitting, otherwise it's least square
     * fitting. c) safeguard, specifies whether to use safeguarded numeric method. d) reset, if
     * fittings have been computed and stored in current object, then reset=true will recompute the
     * fittings based on user input and replace the existing one. \param degree Integer, order of
     * polynomials used for local fittings. \param interp Boolean, true=Interpolation, false=least
     * square fitting. \param safeguard Boolean, true=using safe guarded method in numerical
     * computing. \param reset Boolean, reset=true will recompute the fittings based on user input
     * and replace the existing one.
     */
    ErrorCode reconstruct3D_surf_geom( int degree, bool interp, bool safeguard, bool reset = false );

    //! \brief Reconstruct a high order surface on given surface mesh
    /** Given a mesh, compute vertex based polynomial fittings for all vertices hosted by current
     * processor. User could specify various degrees for different vertices. It assumes that the
     * input degrees for vertices stored in the same order as that this class stores vertices: 1)
     * reconstruction will be only performed at vertices hosted by current processor, thus input
     * npts should match the number of hosted vertices. 2) all hosted vertices will be stored in a
     * MOAB::Range object, degrees for all these vertices should be stored in degrees as the same
     * order in the MOAB::Range object The result will be stored interally for later usage of
     * evalution. \param npts Integer size of array pointed by degrees, used for check \param
     * degrees Integer arrray, order of polynomials for local fitting at all hosted vertices \param
     * interp Boolean, true=Interpolation, false=least square fitting. \param safeguard Boolean,
     * true=using safe guarded method in numerical computing. \param reset Boolean, reset=true will
     * recompute the fittings based on user input and replace the existing one.
     */
    ErrorCode reconstruct3D_surf_geom( size_t npts, int* degrees, bool* interps, bool safeguard, bool reset = false );

    //! \brief Reconstruct a high order curve on given curve mesh
    /** Given a curve mesh, compute vertex based polynomail fittings for all vertices hosted by
     * current processor. The vertex based fitting is done by perfoming three one-parameter fittings
     * along each axis, i.e. x,y,z. The result will be stored interally for later usage of
     * evalution. \param degree Integer, order of polynomials used for local fittings. \param interp
     * Boolean, true=Interpolation, false=least square fitting. \param safeguard Boolean, true=using
     * safe guarded method in numerical computing. \param reset Boolean, reset=true will recompute
     * the fittings based on user input and replace the existing one.
     */
    ErrorCode reconstruct3D_curve_geom( int degree, bool interp, bool safeguard, bool reset = false );

    //! \brief Reconstruct a high order curve on given curve mesh
    /** Given a curve mesh, compute vertex based polynomail fittings for all vertices hosted by
     * current processor. The vertex based fitting is done by perfoming three one-parameter fittings
     * along each axis, i.e. x,y,z. User could specify various degrees for different vertices. It
     * assumes that the input degrees for vertices stored in the same order as that this class
     * stores vertices: 1) reconstruction will be only performed at vertices hosted by current
     * processor, thus input npts should match the number of hosted vertices. 2) all hosted vertices
     * will be stored in a MOAB::Range object, degrees for all these vertices should be stored in
     * degrees as the same order in the MOAB::Range object The result will be stored interally for
     * later usage of evalution. \param npts Integer size of array pointed by degrees, used for
     * check \param degrees Integer arrray, order of polynomials for local fitting at all hosted
     * vertices. \param interp Boolean, true=Interpolation, false=least square fitting. \param
     * safeguard Boolean, true=using safe guarded method in numerical computing. \param reset
     * Boolean, reset=true will recompute the fittings based on user input and replace the existing
     * one.
     */
    ErrorCode reconstruct3D_curve_geom( size_t npts, int* degrees, bool* interps, bool safeguard, bool reset = false );

    //! \brief Construct vertex based polynomial fitting on a surface mesh
    /** Given a vertex on a surface mesh, construct a local fitting around this vertex. Stencils
     * around this vertex will be selected according to input degree and if data is noise. Local
     * uv-plane will be the estimated tangent plane at this vertex. minpnts will be used to specify
     * the minimum number allowed in the local stencil. The result will be returned to user by
     * preallocated memory coords, degree_out, coeffs. \param vid EntityHandle, the fitting will be
     * performed around this vertex for the local height function over the uv-plane. \param interp
     * Boolean, true=Interpolation, false=least square fitting. \param degree Integer, order of
     * polynomials used for local fittings. \param minpnts Integer, the allowed minimum number of
     * vertices in local stencil. If too small, the resulted fitting might be low order accurate. If
     * too large, it may introduce overfitting. \param safeguard Boolean, true=using safe guarded
     * method in numerical computing. \param coords Pointer to double, preallocated memory by user,
     * should have at least 9 doubles; stores the global coordinates of local coordinates system uvw
     * directions. \param degree_out Pointer to integer, used to store the degree of resulted
     * fitting \param coeffs, Pointer to double, preallocated memory for coefficients of local
     * fittings, should have at least (degree+2)(degree+1)/2 doubles.
     */
    ErrorCode polyfit3d_walf_surf_vertex( const EntityHandle vid,
                                          const bool interp,
                                          int degree,
                                          int minpnts,
                                          const bool safeguard,
                                          const int ncoords,
                                          double* coords,
                                          int* degree_out,
                                          const int ncoeffs,
                                          double* coeffs );

    //! \brief Construct vertex based polynomial fitting on a curve mesh
    /** Given a vertex on a curve mesh, construct three one-parameter local fittings for each
     * coordinates axis around this vertex. Stencils around this vertex will be selected according
     * to input degree and if data is noise. Local u-line, or the single parameter will be the
     * estimated tangent line at this vertex. On each axis of xyz, a polynomial fitting will be
     * performed according to user input. minpnts will be used to specify the minimum number allowed
     * in the local stencil. The result will be returned to user by preallocated memory coords,
     * degree_out, coeffs. \param vid EntityHandle, the fittings will be performed around this
     * vertex. \param interp Boolean, true=Interpolation, false=least square fitting. \param degree
     * Integer, order of polynomials used for local fittings. \param minpnts Integer, the allowed
     * minimum number of vertices in local stencil. If too small, the resulted fitting might be low
     * order accurate. If too large, it may introduce overfitting. \param safeguard Boolean,
     * true=using safe guarded method in numerical computing. \param coords Pointer to double,
     * preallocated memory by user, should have at least 3 doubles; stores the global coordinates of
     * local coordinate system u direction. \param degree_out Pointer to integer, used to store the
     * degree of resulted fitting \param coeffs, Pointer to double, preallocated memory for
     * coefficients of local fittings, should have at least 3*(degree+1) doubles.
     */
    ErrorCode polyfit3d_walf_curve_vertex( const EntityHandle vid,
                                           const bool interp,
                                           int degree,
                                           int minpnts,
                                           const bool safeguard,
                                           const int ncoords,
                                           double* coords,
                                           int* degree_out,
                                           const int ncoeffs,
                                           double* coeffs );

    //! \brief Perform high order projection of points in an element, using estimated geometry by
    //! reconstruction class
    /** Given an element on the input mesh, and new points in this element, represented as natural
     * coordinates in element, estimate their position in surface. This is done by weighted
     * averaging of local fittings: for each vertex of this elment, a fitting has been computed and
     * the new points could be projected by this fitting. The final result of projection is the
     * weighted average of these projections, weights are chosen as the barycentric coordinates of
     * the point in this element. The result will be returned to the user preallocated memory \param
     * elem EntityHandle, the element on which to perform high order projection. \param nvpe
     * Integer, number of nodes of this element, triangle is 3, quad is four. \param npts2fit
     * Integer, number of points lying in elem to be projected. \param naturalcoords2fit Pointer to
     * array of doubles, size=nvpe*npts2fit, natural coordinates in elem of points to be projected.
     * \param newcoords Pointer to array of doubles, preallocated by user, size=3*npts2fit,
     * estimated positions of input points.
     */
    ErrorCode hiproj_walf_in_element( EntityHandle elem,
                                      const int nvpe,
                                      const int npts2fit,
                                      const double* naturalcoords2fit,
                                      double* newcoords );

    //! \brief Perform high order projection of points around a vertex, using estimated geometry by
    //! reconstruction class
    /** Given an vertex on the input mesh, and new points around this vertex, estimate their
     * position in surface. This is done by first projecting input points onto the local uv-plane
     * around this vertex and use the precomputed local fitting to estimate the ideal position of
     * input points. The result will be returned to the user preallocated memory \param vid
     * EntityHandle, the vertex around which to perform high order projection. \param npts2fit
     * Integer, number of points lying around vid to be fitted. \param coords2fit Pointer to array
     * of doubles, size=3*npts2fit, current coordinates of points to be projected. \param newcoords
     * Pointer to array of doubles, preallocated by user, size=3*npts2fit, estimated positions of
     * input points.
     */
    ErrorCode hiproj_walf_around_vertex( EntityHandle vid,
                                         const int npts2fit,
                                         const double* coords2fit,
                                         double* hiproj_new );

    //! \brief Perform high order projection of points around a center vertex, assume geometry is
    //! surface
    /** Given a vertex position and the local fitting parameter around this vertex, estimate the
     * ideal position of input position according to the local fitting. This is done by first
     * projecting input points onto the local uv-plane around this vertex and use the given fitting
     * to estimate the ideal position of input points. The result will be returned to user
     * preallocated memory \param local_origin Pointer to 3 doubles, coordinates of the center
     * vertex \param local_coords Pointer to 9 doubles, global coordinates of directions of local
     * uvw coordinates axis at center vertex \param local_deg Integer, order of local polynomial
     * fitting \param local_coeffs Pointer to array of doubles, size=(local_deg+2)(local_deg+1)/2,
     * coefficients of local polynomial fittings, in monomial basis \param interp Boolean,
     * true=local fitting is interpolation, false=local fitting is least square fitting \param
     * npts2fit Integer, number of points to be estimated, around the center vertices \param
     * coords2fit Pointer to array of doubles, size=3*npts2fit, current coordinates of points to be
     * estimated \param hiproj_new Pointer to array of doubles, size=3*npts2fit, memory preallocated
     * by user to store the fitting/estimated positions of input points.
     */
    void walf3d_surf_vertex_eval( const double* local_origin,
                                  const double* local_coords,
                                  const int local_deg,
                                  const double* local_coeffs,
                                  const bool interp,
                                  const int npts2fit,
                                  const double* coords2fit,
                                  double* hiproj_new );

    //! \brief Perform high order projection of points around a center vertex, assume geometry is
    //! curve
    /** Given a vertex position and the local one-parameter fittings parameter around this vertex,
     * estimate the ideal position of input position according to the local fittings. This is done
     * by first projecting input points onto the local u-direction at this vertex and then use the
     * value u as parameter for the three fittings, one for each coordinates axis of xyz. The result
     * will be returned to user preallocated memory \param local_origin Pointer to 3 doubles,
     * coordinates of the center vertex \param local_coords Pointer to 3 doubles, global coordinates
     * of direction of local u coordinate axis at center vertex \param local_deg Integer, order of
     * local polynomial fitting \param local_coeffs Pointer to array of doubles,
     * size=3*(local_deg+1), coefficients of three local polynomial fittings, in monomial basis. For
     * each fitting, local_deg+1 parameters. \param interp Boolean, true=local fitting is
     * interpolation, false=local fitting is least square fitting \param npts2fit Integer, number of
     * points to be estimated, around the center vertices \param coords2fit Pointer to array of
     * doubles, size=3*npts2fit, current coordinates of points to be estimated \param hiproj_new
     * Pointer to array of doubles, size=3*npts2fit, memory preallocated by user to store the
     * fitting/estimated positions of input points.
     */
    void walf3d_curve_vertex_eval( const double* local_origin,
                                   const double* local_coords,
                                   const int local_deg,
                                   const double* local_coeffs,
                                   const bool interp,
                                   const int npts2fit,
                                   const double* coords2fit,
                                   double* hiproj_new );

    //! \brief Get interally stored fitting results
    /** Get fittings results of a vertex, stored internally, results will be writtend to user
     * provided memory \param vid EntityHandle, a vertex in _verts2rec \param geomtype GEOMTYPE, one
     * of HISURFACE,HI3DCURVE,HI2DCURVE \param coords vector, global coordinates of local uvw
     * coordinate system axis directions will be appended to the end of coords \param degree_out
     * Reference to Integer, order of polynomial fittings for vid \param coeffs vector, coefficients
     * of local polynomial fittings in monomial basis will be appended to the end of coeffs \param
     * interp Reference to Boolean, true =  interpolation
     */
    bool get_fittings_data( EntityHandle vid,
                            GEOMTYPE& geomtype,
                            std::vector< double >& coords,
                            int& degree_out,
                            std::vector< double >& coeffs,
                            bool& interp );

    // Helper function: estimate require number of ghost layers in parallel setting
    static int estimate_num_ghost_layers( int degree, bool interp = false )
    {
        return 1 + ( interp ? ( ( degree + 1 ) >> 1 ) + ( ( degree + 1 ) & 1 )
                            : ( ( degree + 2 ) >> 1 ) + ( ( degree + 2 ) & 1 ) );
    };

  protected:
    Core* mbImpl;
    ParallelComm* pcomm;
    HalfFacetRep* ahf;
    // prevent copying
    HiReconstruction( const HiReconstruction& source );
    HiReconstruction& operator=( const HiReconstruction& right );

    // mesh on which to perform reconstruction
    EntityHandle _mesh2rec;
    //_verts2rec all locally hosted vertices, in parallel might be different from _invert which is
    // all the vertices in _mesh2rec, including ghost vertices
    Range _verts2rec, _inverts, _inedges, _infaces, _incells;
    size_t _nv2rec;  // size of _verts2rec

    int _MAXPNTS, _MINPNTS;
    double _MINEPS;

    // in curve mesh, _hasderiv=true means vertex tangent vectors have been computed over _verts2rec
    // in surface mesh, _hasderiv=true means vertex normals have been computed over _verts2rec
    bool _hasderiv;

    GEOMTYPE _geom;
    int _dim;
    bool _hasfittings;
    bool _initfittings;
    std::vector< double > _local_coords;
    std::vector< double > _local_fit_coeffs;
    std::vector< size_t > _vertID2coeffID;
    std::vector< int > _degrees_out;
    std::vector< bool > _interps;

    // Estimate stencil size
    int estimate_num_rings( int degree, bool interp );

    //! \brief Given a vertex, return the incident elements with dimension elemdim
    /** Wrapper of MOAB Core->get_adjacencies and HalfRep->get_up_adjacencies, depends on if USE_AHF
     * is defined \param vid EntityHandle of vertex \param elemdim Integer, dimension of elements
     * incidented in vid \param adjents vector<EntityHandle>, container which push incident elements
     * in
     */
    ErrorCode vertex_get_incident_elements( const EntityHandle& vid,
                                            const int elemdim,
                                            std::vector< EntityHandle >& adjents );

    //! \brief Get n-ring neighbor vertices, assuming curve/surface mesh, not volume mesh
    /** Given a vertex, find its n-ring neighbor vertices including itself in _mesrh2rec.
     * 1-ring neighbor vertices of a vertex are the vertices connected with this vertex with an edge
     * n-ring vertices are obtained first get the 1-ring vertices and then get the 1-ring of these
     * vertices, and so on \param vid EntityHandle, vertex around which to get n-ring vertices
     * \param ring Integer, number of rings
     * \param minpnts Integer, number of minimum vertices to obtain, if the input ring could not
     * provide enough vertices, i.e. more than minpnts, then expand the number of rings \param ngbvs
     * Range, the n-ring vertices of vid, including vid. If too many points found, i.e. more than
     * _MAXPNTS, then terminate early.
     */
    ErrorCode obtain_nring_ngbvs( const EntityHandle vid, int ring, const int minpnts, Range& ngbvs );

    /** Initialize the storage for fitting results over _mesh2rec, curve/surface mesh
     * Two options are provided: a) use uniform degree for all vertices b) use customized degrees
     * for different vertices After calling of initializing functions, _initfitting is set to be
     * true, the fitting result could be stored internally
     */
    void initialize_surf_geom( const int degree );
    void initialize_surf_geom( const size_t npts, const int* degrees );
    void initialize_3Dcurve_geom( const int degree );
    void initialize_3Dcurve_geom( const size_t npts, const int* degrees );

    /** Save fitting results of a vertex into internal storage
     * \param vid EntityHandle, a vertex in _mesh2rec, in _verts2rec
     * \param coords Pointer to double array, global coordinates of local uvw coordinate system axis
     * directions \param degree_out Integer, order of polynomial fittings for vid \param coeffs
     * Pointer to double array, coefficients of local polynomial fittings in monomial basis \param
     * interp Boolean, true =  interpolation
     */
    // ErrorCode set_geom_data_surf(const EntityHandle vid, const double* coords, const double
    // degree_out, const double* coeffs, bool interp); ErrorCode set_geom_data_3Dcurve(const
    // EntityHandle vid, const double* coords, const double degree_out, const double* coeffs, bool
    // interp);

    /** Compute area weighted average vertex normals for given vertex, assuming surface mesh
     * For arbitrary polygon mesh, use incident two edges of each incident polygon of this vertex to
     * form a triangle, then use these incident "triangles" to compute area weighted average vertex
     * normals \param vid EntityHandle, vertex in _mesh2rec, might be ghost vertex \param nrm
     * Pointer to 3-doubles array, preallocated by user
     */
    ErrorCode average_vertex_normal( const EntityHandle vid, double* nrm );

    /** Compute weighted average vertex normals for all vertices in _verts2rec, not including ghost
     * vertices, results are stored interally in _local_coords
     */
    ErrorCode compute_average_vertex_normals_surf();

    /** Return the normals of given vertices in a Range, writing to preallocated memory
     * If normals have been computed and stored, just access them
     * If not, compute on the fly
     * \param vertsh Range, EntityHandles of vertices
     * \param nrms Pointer of array of doubles, size = 3*vertsh.size()
     */
    ErrorCode get_normals_surf( const Range& vertsh, double* nrms );

    /** Compute area weighted average vertex tangent vector for given vertex, assuming curve mesh
     * Use incident two edges of vertex as estimatation of tangent vectors, weighted by length
     * \param vid EntityHandle, vertex in _mesh2rec, might be ghost vertex
     * \param tang Pointer to 3-doubles array, preallocated by user
     */
    ErrorCode average_vertex_tangent( const EntityHandle vid, double* tang );

    /** Compute weighted average vertex tangent vectors for all vertices in _verts2rec, not
     * including ghost vertices, results are stored interally in _local_coords
     */
    ErrorCode compute_average_vertex_tangents_curve();

    /** Return the tangent vectors of given vertices in a Range, writing to preallocated memory
     * If tangent vectors have been computed and stored, just access them
     * If not, compute on the fly
     * \param vertsh Range, EntityHandles of vertices
     * \param tangs Pointer of array of doubles, size = 3*vertsh.size()
     */
    ErrorCode get_tangents_curve( const Range& vertsh, double* tangs );

    //! \brief Compute local coordinates system of a vertex, and perform vertex based polynomial
    //! fittings of local height function
    /** This function take the first vertex of input as center, and build local uv-plane by
     * estimating vertex normals and tangent planes Then other vertices forms vectors starting from
     * center and then are projectd onto this uv-plane to form a local height function. Local
     * fitting of this local height function is performed in WLS sense, according if interpolation
     * required or not. \param nverts Integer, number of vertices of input \param ngbcors Pointer to
     * array of doubles, size = 3*nverts, coordinates of input vertices, first will be center \param
     * ngbnrms Pointer to array of doubles, size = 3*nverts, vertex normals of input vertices \param
     * degree Integer, user specified fitting degree \param interp Boolean, user input,
     * interpolation or not \param safeguard Boolean, true = use safeguarded numerical method in
     * computing \param ncoords Integer, size of *coords, should be 9, used for check \param coords
     * Pointer to array of doubles, preallocated memory for storing the glocal coordinates of local
     * uvw axis directions \param ncoeffs Integer, size of *coeffs, should be
     * (degree+2)(degree+1)/2, used for check \param coeffs Pointer to array of doubles,
     * preallocated memory for storing coefficients of local fittings in monomial basis \param
     * degree_out Pointer to integer, order of resulted polynomial of fitting, could be downgraded
     * due to numerical issues \param degree_pnt Pointer to integer, polynomial fitting order
     * determined by stencil size/number of points \param degree_qr Pointer to integer, polynomial
     * fitting order determined by Vandermonde system condition number
     */
    void polyfit3d_surf_get_coeff( const int nverts,
                                   const double* ngbcors,
                                   const double* ngbnrms,
                                   int degree,
                                   const bool interp,
                                   const bool safeguard,
                                   const int ncoords,
                                   double* coords,
                                   const int ncoeffs,
                                   double* coeffs,
                                   int* degree_out,
                                   int* degree_pnt,
                                   int* degree_qr );
    //! \brief Form and solve Vandermonde system of bi-variables
    void eval_vander_bivar_cmf( const int npts2fit,
                                const double* us,
                                const int ndim,
                                double* bs,
                                int degree,
                                const double* ws,
                                const bool interp,
                                const bool safeguard,
                                int* degree_out,
                                int* degree_pnt,
                                int* degree_qr );

    //! \brief Compute local single variable coordinate system of a vertex, and perform vertex based
    //! polynomial fittings of three global coordinates axis
    /** This function take the first vertex of input as center, and build local u-line by estimating
     * tangent vector Then other vertices form vectors originating from center and vectors then are
     * projectd onto this u-plane to form three local height functions, one for each coordinates
     * axis. Local fitting of these local height functions are performed in WLS sense, according if
     * interpolation required or not. \param nverts Integer, number of vertices of input \param
     * ngbcors Pointer to array of doubles, size = 3*nverts, coordinates of input vertices, first
     * will be center \param ngbtangs Pointer to array of doubles, size = 3*nverts, vertex tangent
     * vectors of input vertices \param degree Integer, user specified fitting degree \param interp
     * Boolean, user input, interpolation or not \param safeguard Boolean, true = use safeguarded
     * numerical method in computing \param ncoords Integer, size of *coords, should be 3, used for
     * check \param coords Pointer to array of doubles, preallocated memory for storing the glocal
     * coordinates of local u axis direction \param ncoeffs Integer, size of *coeffs, should be
     * 3*(degree+1), used for check \param coeffs Pointer to array of doubles, preallocated memory
     * for storing coefficients of local fittings in monomial basis \param degree_out Pointer to
     * integer, order of resulted polynomial of fitting, could be downgraded due to numerical issues
     */
    void polyfit3d_curve_get_coeff( const int nverts,
                                    const double* ngbcors,
                                    const double* ngbtangs,
                                    int degree,
                                    const bool interp,
                                    const bool safeguard,
                                    const int ncoords,
                                    double* coords,
                                    const int ncoeffs,
                                    double* coeffs,
                                    int* degree_out );
    //! \brief Form and solve Vandermonde system of single-variables
    void eval_vander_univar_cmf( const int npts2fit,
                                 const double* us,
                                 const int ndim,
                                 double* bs,
                                 int degree,
                                 const double* ws,
                                 const bool interp,
                                 const bool safeguard,
                                 int* degree_out );
    //! \brief Compute weights for points selected in weighted least square fittigns
    int compute_weights( const int nrows,
                         const int ncols,
                         const double* us,
                         const int nngbs,
                         const double* ngbnrms,
                         const int degree,
                         const double toler,
                         double* ws );
    //! \brief Check the correctness of barycentric coordination, wi>=0 and sum(wi)=1
    bool check_barycentric_coords( const int nws, const double* naturalcoords );
};  // class HiReconstruction
}  // namespace moab
#endif