int GaussLegendreTet(int n1, int n2, int n3, IntPt *pts)
{
/* get degenerate n1Xn2Xn3 Gauss-Legendre scheme to integrate over a tet */
int i,j,k,index=0;
double *pt1,*pt2,*pt3,*wt1,*wt2,*wt3,dJ;
gmshGaussLegendre1D(n1,&pt1,&wt1);
gmshGaussLegendre1D(n2,&pt2,&wt2);
gmshGaussLegendre1D(n3,&pt3,&wt3);
for(i=0; i < n1; i++) {
for(j=0; j < n2; j++) {
for(k=0; k < n3; k++) {
brickToTet(pt1[i],pt2[j],pt3[k],&(pts[index].pt[0]),
&(pts[index].pt[1]),&(pts[index].pt[2]),&dJ);
pts[index++].weight = dJ*wt1[i]*wt2[j]*wt3[k];
}
}
}
return index;
}
int GaussLegendreTet(int n1,int n2,int n3,double GLrstw[][4],double *GLwt) {
/* get degenerate n1Xn2Xn3 Gauss-Legendre scheme to integrate over a tet */
int i,j,k,index=0;
double *pt1,*pt2,*pt3,*wt1,*wt2,*wt3,dJ;
const double six=6.000000000000000;
GaussLegendre1D(n1,&pt1,&wt1);
GaussLegendre1D(n2,&pt2,&wt2);
GaussLegendre1D(n3,&pt3,&wt3);
for(i=0; i < n1; i++) {
for(j=0; j < n2; j++) {
for(k=0; k < n3; k++) {
brickToTet(pt1[i],pt2[j],pt3[k],&GLrstw[index][0],
&GLrstw[index][1],&GLrstw[index][2],&dJ);
GLrstw[index][3] = 1.0e0-GLrstw[index][0]-GLrstw[index][1]
-GLrstw[index][2];
GLwt[index++] = dJ*wt1[i]*wt2[j]*wt3[k]*six;
}
}
}
return index;
}