#define RCSID "$Id: Gauss_Tetrahedron.c,v 1.17 2006/02/26 00:42:54 geuzaine Exp $"
/*
 * Copyright (C) 1997-2006 P. Dular, C. Geuzaine
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA.
 *
 * Please report all bugs and problems to <getdp@geuz.org>.
 */

#include "GetDP.h"
#include "Quadrature.h"
#include "Gauss_Tetrahedron.h"

/* Gauss integration over a tetrahedron */

void  Gauss_Tetrahedron (int Nbr_Points, int Num,
			 double *u, double *v, double *w, double *wght) {

  GetDP_Begin("Gauss_Tetrahedron");

  switch (Nbr_Points) {

  case  1 : 
    *u = xtet1 [Num] ; *v = ytet1 [Num] ; *w = ztet1 [Num] ;
    *wght = ptet1 [Num] ; break ;

  case  4 : 
    *u = xtet4 [Num] ; *v = ytet4 [Num] ; *w = ztet4 [Num] ;
    *wght = ptet4 [Num] ; break ;

  case  5 : 
    *u = xtet5 [Num] ; *v = ytet5 [Num] ; *w = ztet5 [Num] ;
    *wght = ptet5 [Num] ; break ;

  case 15 : 
    *u = xtet15[Num] ; *v = ytet15[Num] ; *w = ztet15[Num] ;
    *wght = ptet15[Num] ; break ;

  case 16 : 
    *u = xtet16[Num] ; *v = ytet16[Num] ; *w = ztet16[Num] ;
    *wght = ptet16[Num] ; break ;

  case 17 : 
    *u = xtet17[Num] ; *v = ytet17[Num] ; *w = ztet17[Num] ;
    *wght = ptet17[Num] ; break ;

  case 29 : 
    *u = xtet29[Num] ; *v = ytet29[Num] ; *w = ztet29[Num] ;
    *wght = ptet29[Num] ; break ;

  default : 
    Msg(DIRECT, ERROR_STR "Wrong number of Gauss Points for Tetrahedron");
    Msg(GERROR, "Valid choices: 1, 4, 5, 15, 16, 17, 29");
    break;
  }

  GetDP_End ;
}


/* Degenerate n1Xn2Xn3 Gauss-Legendre scheme to integrate over a tet */

int gltet[MAX_LINE_POINTS] = {-1};
double *glxtet[MAX_LINE_POINTS], *glytet[MAX_LINE_POINTS] ;
double *glztet[MAX_LINE_POINTS], *glptet[MAX_LINE_POINTS];

void hexToTet(double xi,double eta, double zeta,
	      double *r, double *s, double *t, double *J) {
  double r1,rs1;

  GetDP_Begin("hexToTet");

  *r = 0.5e0*(1.0e0+xi);
  r1 = 1.0e0-(*r);
  *s = 0.5e0*(1.0e0+eta)*r1;
  rs1 = 1.0e0-(*r)-(*s);
  *t = 0.5e0*(1.0e0+zeta)*rs1;
  *J = 0.125e0*r1*rs1;

  GetDP_End ;
}

void  GaussLegendre_Tetrahedron (int Nbr_Points, int Num,
				 double *u, double *v, double *w, double *wght) {
  int i,j,k,index=0,nb;
  double pt1,pt2,pt3,wt1,wt2,wt3,dJ,dum;

  GetDP_Begin("GaussLegendre_Tetrahedron");

  nb = (int)pow((double)Nbr_Points, 1./3.);

  if(nb*nb*nb != Nbr_Points || nb > MAX_LINE_POINTS)
    Msg(GERROR, "Number of points should be n^3 with n in [1,%d]", MAX_LINE_POINTS) ;

  if(gltet[0] < 0) for(i=0 ; i < MAX_LINE_POINTS ; i++) gltet[i] = 0 ;

  if(!gltet[nb-1]){
    Msg(INFO, "Computing degenerate GaussLegendre %dX%dX%d for Tetrahedron", 
	nb, nb, nb);
    glxtet[nb-1] = (double*)Malloc(Nbr_Points*sizeof(double));
    glytet[nb-1] = (double*)Malloc(Nbr_Points*sizeof(double));
    glztet[nb-1] = (double*)Malloc(Nbr_Points*sizeof(double));
    glptet[nb-1] = (double*)Malloc(Nbr_Points*sizeof(double));
    for(i=0; i < nb; i++) {
      Gauss_Line(nb, i, &pt1, &dum, &dum, &wt1);
      for(j=0; j < nb; j++) {
	Gauss_Line(nb, j, &pt2, &dum, &dum, &wt2);
	for(k=0; k < nb; k++) {
	  Gauss_Line(nb, k, &pt3, &dum, &dum, &wt3);
	  hexToTet(pt1, pt2, pt3, &glxtet[nb-1][index], &glytet[nb-1][index], 
		   &glztet[nb-1][index], &dJ);
	  glptet[nb-1][index++] = dJ*wt1*wt2*wt3;
	}
      }
    }
    gltet[nb-1] = 1;
  }

  *u = glxtet[nb-1][Num] ; *v = glytet[nb-1][Num] ; *w = glztet[nb-1][Num] ;
  *wght = glptet[nb-1][Num] ;

  GetDP_End ;
}