xref: /petsc/src/dm/impls/plex/plexgeometry.c (revision 7c1f96392e1878ed304042e2b6e5cdb3be0530d0)
1 #include <petsc-private/dmpleximpl.h>   /*I      "petscdmplex.h"   I*/
2 
3 #undef __FUNCT__
4 #define __FUNCT__ "DMPlexLocatePoint_Simplex_2D_Internal"
5 static PetscErrorCode DMPlexLocatePoint_Simplex_2D_Internal(DM dm, const PetscScalar point[], PetscInt c, PetscInt *cell)
6 {
7   const PetscInt embedDim = 2;
8   PetscReal      x        = PetscRealPart(point[0]);
9   PetscReal      y        = PetscRealPart(point[1]);
10   PetscReal      v0[2], J[4], invJ[4], detJ;
11   PetscReal      xi, eta;
12   PetscErrorCode ierr;
13 
14   PetscFunctionBegin;
15   ierr = DMPlexComputeCellGeometry(dm, c, v0, J, invJ, &detJ);CHKERRQ(ierr);
16   xi  = invJ[0*embedDim+0]*(x - v0[0]) + invJ[0*embedDim+1]*(y - v0[1]);
17   eta = invJ[1*embedDim+0]*(x - v0[0]) + invJ[1*embedDim+1]*(y - v0[1]);
18 
19   if ((xi >= 0.0) && (eta >= 0.0) && (xi + eta <= 2.0)) *cell = c;
20   else *cell = -1;
21   PetscFunctionReturn(0);
22 }
23 
24 #undef __FUNCT__
25 #define __FUNCT__ "DMPlexLocatePoint_General_2D_Internal"
26 static PetscErrorCode DMPlexLocatePoint_General_2D_Internal(DM dm, const PetscScalar point[], PetscInt c, PetscInt *cell)
27 {
28   PetscSection       coordSection;
29   Vec             coordsLocal;
30   PetscScalar    *coords;
31   const PetscInt  faces[8]  = {0, 1, 1, 2, 2, 3, 3, 0};
32   PetscReal       x         = PetscRealPart(point[0]);
33   PetscReal       y         = PetscRealPart(point[1]);
34   PetscInt        crossings = 0, f;
35   PetscErrorCode  ierr;
36 
37   PetscFunctionBegin;
38   ierr = DMGetCoordinatesLocal(dm, &coordsLocal);CHKERRQ(ierr);
39   ierr = DMPlexGetCoordinateSection(dm, &coordSection);CHKERRQ(ierr);
40   ierr = DMPlexVecGetClosure(dm, coordSection, coordsLocal, c, NULL, &coords);CHKERRQ(ierr);
41   for (f = 0; f < 4; ++f) {
42     PetscReal x_i   = PetscRealPart(coords[faces[2*f+0]*2+0]);
43     PetscReal y_i   = PetscRealPart(coords[faces[2*f+0]*2+1]);
44     PetscReal x_j   = PetscRealPart(coords[faces[2*f+1]*2+0]);
45     PetscReal y_j   = PetscRealPart(coords[faces[2*f+1]*2+1]);
46     PetscReal slope = (y_j - y_i) / (x_j - x_i);
47     PetscBool cond1 = (x_i <= x) && (x < x_j) ? PETSC_TRUE : PETSC_FALSE;
48     PetscBool cond2 = (x_j <= x) && (x < x_i) ? PETSC_TRUE : PETSC_FALSE;
49     PetscBool above = (y < slope * (x - x_i) + y_i) ? PETSC_TRUE : PETSC_FALSE;
50     if ((cond1 || cond2)  && above) ++crossings;
51   }
52   if (crossings % 2) *cell = c;
53   else *cell = -1;
54   ierr = DMPlexVecRestoreClosure(dm, coordSection, coordsLocal, c, NULL, &coords);CHKERRQ(ierr);
55   PetscFunctionReturn(0);
56 }
57 
58 #undef __FUNCT__
59 #define __FUNCT__ "DMPlexLocatePoint_Simplex_3D_Internal"
60 static PetscErrorCode DMPlexLocatePoint_Simplex_3D_Internal(DM dm, const PetscScalar point[], PetscInt c, PetscInt *cell)
61 {
62   const PetscInt embedDim = 3;
63   PetscReal      v0[3], J[9], invJ[9], detJ;
64   PetscReal      x = PetscRealPart(point[0]);
65   PetscReal      y = PetscRealPart(point[1]);
66   PetscReal      z = PetscRealPart(point[2]);
67   PetscReal      xi, eta, zeta;
68   PetscErrorCode ierr;
69 
70   PetscFunctionBegin;
71   ierr = DMPlexComputeCellGeometry(dm, c, v0, J, invJ, &detJ);CHKERRQ(ierr);
72   xi   = invJ[0*embedDim+0]*(x - v0[0]) + invJ[0*embedDim+1]*(y - v0[1]) + invJ[0*embedDim+2]*(z - v0[2]);
73   eta  = invJ[1*embedDim+0]*(x - v0[0]) + invJ[1*embedDim+1]*(y - v0[1]) + invJ[1*embedDim+2]*(z - v0[2]);
74   zeta = invJ[2*embedDim+0]*(x - v0[0]) + invJ[2*embedDim+1]*(y - v0[1]) + invJ[2*embedDim+2]*(z - v0[2]);
75 
76   if ((xi >= 0.0) && (eta >= 0.0) && (zeta >= 0.0) && (xi + eta + zeta <= 2.0)) *cell = c;
77   else *cell = -1;
78   PetscFunctionReturn(0);
79 }
80 
81 #undef __FUNCT__
82 #define __FUNCT__ "DMPlexLocatePoint_General_3D_Internal"
83 static PetscErrorCode DMPlexLocatePoint_General_3D_Internal(DM dm, const PetscScalar point[], PetscInt c, PetscInt *cell)
84 {
85   PetscSection       coordSection;
86   Vec            coordsLocal;
87   PetscScalar   *coords;
88   const PetscInt faces[24] = {0, 1, 2, 3,  5, 4, 7, 6,  1, 0, 4, 5,
89                               3, 2, 6, 7,  1, 5, 6, 2,  0, 3, 7, 4};
90   PetscBool      found = PETSC_TRUE;
91   PetscInt       f;
92   PetscErrorCode ierr;
93 
94   PetscFunctionBegin;
95   ierr = DMGetCoordinatesLocal(dm, &coordsLocal);CHKERRQ(ierr);
96   ierr = DMPlexGetCoordinateSection(dm, &coordSection);CHKERRQ(ierr);
97   ierr = DMPlexVecGetClosure(dm, coordSection, coordsLocal, c, NULL, &coords);CHKERRQ(ierr);
98   for (f = 0; f < 6; ++f) {
99     /* Check the point is under plane */
100     /*   Get face normal */
101     PetscReal v_i[3];
102     PetscReal v_j[3];
103     PetscReal normal[3];
104     PetscReal pp[3];
105     PetscReal dot;
106 
107     v_i[0]    = PetscRealPart(coords[faces[f*4+3]*3+0]-coords[faces[f*4+0]*3+0]);
108     v_i[1]    = PetscRealPart(coords[faces[f*4+3]*3+1]-coords[faces[f*4+0]*3+1]);
109     v_i[2]    = PetscRealPart(coords[faces[f*4+3]*3+2]-coords[faces[f*4+0]*3+2]);
110     v_j[0]    = PetscRealPart(coords[faces[f*4+1]*3+0]-coords[faces[f*4+0]*3+0]);
111     v_j[1]    = PetscRealPart(coords[faces[f*4+1]*3+1]-coords[faces[f*4+0]*3+1]);
112     v_j[2]    = PetscRealPart(coords[faces[f*4+1]*3+2]-coords[faces[f*4+0]*3+2]);
113     normal[0] = v_i[1]*v_j[2] - v_i[2]*v_j[1];
114     normal[1] = v_i[2]*v_j[0] - v_i[0]*v_j[2];
115     normal[2] = v_i[0]*v_j[1] - v_i[1]*v_j[0];
116     pp[0]     = PetscRealPart(coords[faces[f*4+0]*3+0] - point[0]);
117     pp[1]     = PetscRealPart(coords[faces[f*4+0]*3+1] - point[1]);
118     pp[2]     = PetscRealPart(coords[faces[f*4+0]*3+2] - point[2]);
119     dot       = normal[0]*pp[0] + normal[1]*pp[1] + normal[2]*pp[2];
120 
121     /* Check that projected point is in face (2D location problem) */
122     if (dot < 0.0) {
123       found = PETSC_FALSE;
124       break;
125     }
126   }
127   if (found) *cell = c;
128   else *cell = -1;
129   ierr = DMPlexVecRestoreClosure(dm, coordSection, coordsLocal, c, NULL, &coords);CHKERRQ(ierr);
130   PetscFunctionReturn(0);
131 }
132 
133 #undef __FUNCT__
134 #define __FUNCT__ "DMLocatePoints_Plex"
135 /*
136  Need to implement using the guess
137 */
138 PetscErrorCode DMLocatePoints_Plex(DM dm, Vec v, IS *cellIS)
139 {
140   PetscInt       cell = -1 /*, guess = -1*/;
141   PetscInt       bs, numPoints, p;
142   PetscInt       dim, cStart, cEnd, cMax, c, coneSize;
143   PetscInt      *cells;
144   PetscScalar   *a;
145   PetscErrorCode ierr;
146 
147   PetscFunctionBegin;
148   ierr = DMPlexGetDimension(dm, &dim);CHKERRQ(ierr);
149   ierr = DMPlexGetHeightStratum(dm, 0, &cStart, &cEnd);CHKERRQ(ierr);
150   ierr = DMPlexGetHybridBounds(dm, &cMax, NULL, NULL, NULL);CHKERRQ(ierr);
151   if (cMax >= 0) cEnd = PetscMin(cEnd, cMax);
152   ierr = VecGetLocalSize(v, &numPoints);CHKERRQ(ierr);
153   ierr = VecGetBlockSize(v, &bs);CHKERRQ(ierr);
154   ierr = VecGetArray(v, &a);CHKERRQ(ierr);
155   if (bs != dim) SETERRQ2(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "Block size for point vector %d must be the mesh coordinate dimension %d", bs, dim);
156   numPoints /= bs;
157   ierr       = PetscMalloc(numPoints * sizeof(PetscInt), &cells);CHKERRQ(ierr);
158   for (p = 0; p < numPoints; ++p) {
159     const PetscScalar *point = &a[p*bs];
160 
161     switch (dim) {
162     case 2:
163       for (c = cStart; c < cEnd; ++c) {
164         ierr = DMPlexGetConeSize(dm, c, &coneSize);CHKERRQ(ierr);
165         switch (coneSize) {
166         case 3:
167           ierr = DMPlexLocatePoint_Simplex_2D_Internal(dm, point, c, &cell);CHKERRQ(ierr);
168           break;
169         case 4:
170           ierr = DMPlexLocatePoint_General_2D_Internal(dm, point, c, &cell);CHKERRQ(ierr);
171           break;
172         default:
173           SETERRQ1(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_OUTOFRANGE, "No point location for cell with cone size %d", coneSize);
174         }
175         if (cell >= 0) break;
176       }
177       break;
178     case 3:
179       for (c = cStart; c < cEnd; ++c) {
180         ierr = DMPlexGetConeSize(dm, c, &coneSize);CHKERRQ(ierr);
181         switch (coneSize) {
182         case 4:
183           ierr = DMPlexLocatePoint_Simplex_3D_Internal(dm, point, c, &cell);CHKERRQ(ierr);
184           break;
185         case 8:
186           ierr = DMPlexLocatePoint_General_3D_Internal(dm, point, c, &cell);CHKERRQ(ierr);
187           break;
188         default:
189           SETERRQ1(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_OUTOFRANGE, "No point location for cell with cone size %d", coneSize);
190         }
191         if (cell >= 0) break;
192       }
193       break;
194     default:
195       SETERRQ1(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_OUTOFRANGE, "No point location for mesh dimension %d", dim);
196     }
197     cells[p] = cell;
198   }
199   ierr = VecRestoreArray(v, &a);CHKERRQ(ierr);
200   ierr = ISCreateGeneral(PETSC_COMM_SELF, numPoints, cells, PETSC_OWN_POINTER, cellIS);CHKERRQ(ierr);
201   PetscFunctionReturn(0);
202 }
203 
204 #undef __FUNCT__
205 #define __FUNCT__ "DMPlexComputeProjection3Dto2D_Internal"
206 /*
207   DMPlexComputeProjection3Dto2D_Internal - Rewrite coordinates to be the 2D projection of the 3D
208 */
209 static PetscErrorCode DMPlexComputeProjection3Dto2D_Internal(PetscScalar coords[])
210 {
211   PetscScalar    x1[3], x2[3], n[3], norm;
212   const PetscInt dim = 3;
213   PetscInt       d, e;
214 
215   PetscFunctionBegin;
216   /* 0) Calculate normal vector */
217   for (d = 0; d < dim; ++d) {
218     x1[d] = coords[1*dim+d] - coords[0*dim+d];
219     x2[d] = coords[2*dim+d] - coords[0*dim+d];
220   }
221   n[0] = x1[1]*x2[2] - x1[2]*x2[1];
222   n[1] = x1[2]*x2[0] - x1[0]*x2[2];
223   n[2] = x1[0]*x2[1] - x1[1]*x2[0];
224   norm = sqrt(n[0]*n[0] + n[1]*n[1] + n[2]*n[2]);
225   n[0] /= norm;
226   n[1] /= norm;
227   n[2] /= norm;
228   /* 1) Take the normal vector and rotate until it is \hat z
229 
230     Let the normal vector be <nx, ny, nz> and alpha = 1/sqrt(1 - nz^2), then
231 
232     R = /  alpha nx nz  alpha ny nz -1/alpha \
233         | -alpha ny     alpha nx        0    |
234         \     nx            ny         nz    /
235 
236     will rotate the normal vector to \hat z
237   */
238   PetscScalar R[9], x1p[3], x2p[3];
239   PetscScalar sqrtz = sqrt(1.0 - n[2]*n[2]), alpha = 1.0/sqrtz;
240 
241   R[0] =  alpha*n[0]*n[2]; R[1] = alpha*n[1]*n[2]; R[2] = -sqrtz;
242   R[3] = -alpha*n[1];      R[4] = alpha*n[0];      R[5] = 0.0;
243   R[6] =  n[0];            R[7] = n[1];            R[8] = n[2];
244   for (d = 0; d < dim; ++d) {
245     x1p[d] = 0.0;
246     x2p[d] = 0.0;
247     for (e = 0; e < dim; ++e) {
248       x1p[d] += R[d*dim+e]*x1[e];
249       x2p[d] += R[d*dim+e]*x2[e];
250     }
251   }
252   if (fabs(x1p[2]) > 1.0e-9) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Invalid rotation calculated");
253   if (fabs(x2p[2]) > 1.0e-9) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Invalid rotation calculated");
254   /* 2) Project to (x, y) */
255   coords[0] = 0.0;
256   coords[1] = 0.0;
257   coords[2] = x1p[0];
258   coords[3] = x1p[1];
259   coords[4] = x2p[0];
260   coords[5] = x2p[1];
261   PetscFunctionReturn(0);
262 }
263 
264 #undef __FUNCT__
265 #define __FUNCT__ "DMPlexComputeTriangleGeometry_Internal"
266 static PetscErrorCode DMPlexComputeTriangleGeometry_Internal(DM dm, PetscInt e, PetscReal v0[], PetscReal J[], PetscReal invJ[], PetscReal *detJ)
267 {
268   PetscSection   coordSection;
269   Vec            coordinates;
270   PetscScalar   *coords;
271   const PetscInt dim = 2;
272   PetscInt       numCoords, d, f;
273   PetscErrorCode ierr;
274 
275   PetscFunctionBegin;
276   ierr = DMGetCoordinatesLocal(dm, &coordinates);CHKERRQ(ierr);
277   ierr = DMPlexGetCoordinateSection(dm, &coordSection);CHKERRQ(ierr);
278   ierr = DMPlexVecGetClosure(dm, coordSection, coordinates, e, &numCoords, &coords);CHKERRQ(ierr);
279   if (numCoords == 9) {
280     ierr = DMPlexComputeProjection3Dto2D_Internal(coords);CHKERRQ(ierr);
281   } else if (numCoords != 6) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "The number of coordinates for this triangle is %d != 6", numCoords);
282   if (v0) {
283     for (d = 0; d < dim; d++) v0[d] = PetscRealPart(coords[d]);
284   }
285   if (J) {
286     for (d = 0; d < dim; d++) {
287       for (f = 0; f < dim; f++) {
288         J[d*dim+f] = 0.5*(PetscRealPart(coords[(f+1)*dim+d]) - PetscRealPart(coords[0*dim+d]));
289       }
290     }
291     *detJ = J[0]*J[3] - J[1]*J[2];
292 #if 0
293     if (detJ < 0.0) {
294       const PetscReal xLength = mesh->periodicity[0];
295 
296       if (xLength != 0.0) {
297         PetscReal v0x = coords[0*dim+0];
298 
299         if (v0x == 0.0) v0x = v0[0] = xLength;
300         for (f = 0; f < dim; f++) {
301           const PetscReal px = coords[(f+1)*dim+0] == 0.0 ? xLength : coords[(f+1)*dim+0];
302 
303           J[0*dim+f] = 0.5*(px - v0x);
304         }
305       }
306       detJ = J[0]*J[3] - J[1]*J[2];
307     }
308 #endif
309     PetscLogFlops(8.0 + 3.0);
310   }
311   if (invJ) {
312     const PetscReal invDet = 1.0/(*detJ);
313 
314     invJ[0] =  invDet*J[3];
315     invJ[1] = -invDet*J[1];
316     invJ[2] = -invDet*J[2];
317     invJ[3] =  invDet*J[0];
318     PetscLogFlops(5.0);
319   }
320   ierr = DMPlexVecRestoreClosure(dm, coordSection, coordinates, e, &numCoords, &coords);CHKERRQ(ierr);
321   PetscFunctionReturn(0);
322 }
323 
324 #undef __FUNCT__
325 #define __FUNCT__ "DMPlexComputeRectangleGeometry_Internal"
326 static PetscErrorCode DMPlexComputeRectangleGeometry_Internal(DM dm, PetscInt e, PetscReal v0[], PetscReal J[], PetscReal invJ[], PetscReal *detJ)
327 {
328   PetscSection   coordSection;
329   Vec            coordinates;
330   PetscScalar   *coords;
331   const PetscInt dim = 2;
332   PetscInt       d, f;
333   PetscErrorCode ierr;
334 
335   PetscFunctionBegin;
336   ierr = DMGetCoordinatesLocal(dm, &coordinates);CHKERRQ(ierr);
337   ierr = DMPlexGetCoordinateSection(dm, &coordSection);CHKERRQ(ierr);
338   ierr = DMPlexVecGetClosure(dm, coordSection, coordinates, e, NULL, &coords);CHKERRQ(ierr);
339   if (v0) {
340     for (d = 0; d < dim; d++) v0[d] = PetscRealPart(coords[d]);
341   }
342   if (J) {
343     for (d = 0; d < dim; d++) {
344       for (f = 0; f < dim; f++) {
345         J[d*dim+f] = 0.5*(PetscRealPart(coords[(f*2+1)*dim+d]) - PetscRealPart(coords[0*dim+d]));
346       }
347     }
348     *detJ = J[0]*J[3] - J[1]*J[2];
349     PetscLogFlops(8.0 + 3.0);
350   }
351   if (invJ) {
352     const PetscReal invDet = 1.0/(*detJ);
353 
354     invJ[0] =  invDet*J[3];
355     invJ[1] = -invDet*J[1];
356     invJ[2] = -invDet*J[2];
357     invJ[3] =  invDet*J[0];
358     PetscLogFlops(5.0);
359   }
360   ierr = DMPlexVecRestoreClosure(dm, coordSection, coordinates, e, NULL, &coords);CHKERRQ(ierr);
361   PetscFunctionReturn(0);
362 }
363 
364 #undef __FUNCT__
365 #define __FUNCT__ "DMPlexComputeTetrahedronGeometry_Internal"
366 static PetscErrorCode DMPlexComputeTetrahedronGeometry_Internal(DM dm, PetscInt e, PetscReal v0[], PetscReal J[], PetscReal invJ[], PetscReal *detJ)
367 {
368   PetscSection   coordSection;
369   Vec            coordinates;
370   PetscScalar   *coords;
371   const PetscInt dim = 3;
372   PetscInt       d, f;
373   PetscErrorCode ierr;
374 
375   PetscFunctionBegin;
376   ierr = DMGetCoordinatesLocal(dm, &coordinates);CHKERRQ(ierr);
377   ierr = DMPlexGetCoordinateSection(dm, &coordSection);CHKERRQ(ierr);
378   ierr = DMPlexVecGetClosure(dm, coordSection, coordinates, e, NULL, &coords);CHKERRQ(ierr);
379   if (v0) {
380     for (d = 0; d < dim; d++) v0[d] = PetscRealPart(coords[d]);
381   }
382   if (J) {
383     for (d = 0; d < dim; d++) {
384       for (f = 0; f < dim; f++) {
385         J[d*dim+f] = 0.5*(PetscRealPart(coords[(f+1)*dim+d]) - PetscRealPart(coords[0*dim+d]));
386       }
387     }
388     /* ??? This does not work with CTetGen: The minus sign is here since I orient the first face to get the outward normal */
389     *detJ = (J[0*3+0]*(J[1*3+1]*J[2*3+2] - J[1*3+2]*J[2*3+1]) +
390              J[0*3+1]*(J[1*3+2]*J[2*3+0] - J[1*3+0]*J[2*3+2]) +
391              J[0*3+2]*(J[1*3+0]*J[2*3+1] - J[1*3+1]*J[2*3+0]));
392     PetscLogFlops(18.0 + 12.0);
393   }
394   if (invJ) {
395     const PetscReal invDet = 1.0/(*detJ);
396 
397     invJ[0*3+0] = invDet*(J[1*3+1]*J[2*3+2] - J[1*3+2]*J[2*3+1]);
398     invJ[0*3+1] = invDet*(J[0*3+2]*J[2*3+1] - J[0*3+1]*J[2*3+2]);
399     invJ[0*3+2] = invDet*(J[0*3+1]*J[1*3+2] - J[0*3+2]*J[1*3+1]);
400     invJ[1*3+0] = invDet*(J[1*3+2]*J[2*3+0] - J[1*3+0]*J[2*3+2]);
401     invJ[1*3+1] = invDet*(J[0*3+0]*J[2*3+2] - J[0*3+2]*J[2*3+0]);
402     invJ[1*3+2] = invDet*(J[0*3+2]*J[1*3+0] - J[0*3+0]*J[1*3+2]);
403     invJ[2*3+0] = invDet*(J[1*3+0]*J[2*3+1] - J[1*3+1]*J[2*3+0]);
404     invJ[2*3+1] = invDet*(J[0*3+1]*J[2*3+0] - J[0*3+0]*J[2*3+1]);
405     invJ[2*3+2] = invDet*(J[0*3+0]*J[1*3+1] - J[0*3+1]*J[1*3+0]);
406     PetscLogFlops(37.0);
407   }
408   ierr = DMPlexVecRestoreClosure(dm, coordSection, coordinates, e, NULL, &coords);CHKERRQ(ierr);
409   PetscFunctionReturn(0);
410 }
411 
412 #undef __FUNCT__
413 #define __FUNCT__ "DMPlexComputeHexahedronGeometry_Internal"
414 static PetscErrorCode DMPlexComputeHexahedronGeometry_Internal(DM dm, PetscInt e, PetscReal v0[], PetscReal J[], PetscReal invJ[], PetscReal *detJ)
415 {
416   PetscSection   coordSection;
417   Vec            coordinates;
418   PetscScalar   *coords;
419   const PetscInt dim = 3;
420   PetscInt       d;
421   PetscErrorCode ierr;
422 
423   PetscFunctionBegin;
424   ierr = DMGetCoordinatesLocal(dm, &coordinates);CHKERRQ(ierr);
425   ierr = DMPlexGetCoordinateSection(dm, &coordSection);CHKERRQ(ierr);
426   ierr = DMPlexVecGetClosure(dm, coordSection, coordinates, e, NULL, &coords);CHKERRQ(ierr);
427   if (v0) {
428     for (d = 0; d < dim; d++) v0[d] = PetscRealPart(coords[d]);
429   }
430   if (J) {
431     for (d = 0; d < dim; d++) {
432       J[d*dim+0] = 0.5*(PetscRealPart(coords[(0+1)*dim+d]) - PetscRealPart(coords[0*dim+d]));
433       J[d*dim+1] = 0.5*(PetscRealPart(coords[(1+1)*dim+d]) - PetscRealPart(coords[0*dim+d]));
434       J[d*dim+2] = 0.5*(PetscRealPart(coords[(3+1)*dim+d]) - PetscRealPart(coords[0*dim+d]));
435     }
436     *detJ = (J[0*3+0]*(J[1*3+1]*J[2*3+2] - J[1*3+2]*J[2*3+1]) +
437              J[0*3+1]*(J[1*3+2]*J[2*3+0] - J[1*3+0]*J[2*3+2]) +
438              J[0*3+2]*(J[1*3+0]*J[2*3+1] - J[1*3+1]*J[2*3+0]));
439     PetscLogFlops(18.0 + 12.0);
440   }
441   if (invJ) {
442     const PetscReal invDet = -1.0/(*detJ);
443 
444     invJ[0*3+0] = invDet*(J[1*3+1]*J[2*3+2] - J[1*3+2]*J[2*3+1]);
445     invJ[0*3+1] = invDet*(J[0*3+2]*J[2*3+1] - J[0*3+1]*J[2*3+2]);
446     invJ[0*3+2] = invDet*(J[0*3+1]*J[1*3+2] - J[0*3+2]*J[1*3+1]);
447     invJ[1*3+0] = invDet*(J[1*3+2]*J[2*3+0] - J[1*3+0]*J[2*3+2]);
448     invJ[1*3+1] = invDet*(J[0*3+0]*J[2*3+2] - J[0*3+2]*J[2*3+0]);
449     invJ[1*3+2] = invDet*(J[0*3+2]*J[1*3+0] - J[0*3+0]*J[1*3+2]);
450     invJ[2*3+0] = invDet*(J[1*3+0]*J[2*3+1] - J[1*3+1]*J[2*3+0]);
451     invJ[2*3+1] = invDet*(J[0*3+1]*J[2*3+0] - J[0*3+0]*J[2*3+1]);
452     invJ[2*3+2] = invDet*(J[0*3+0]*J[1*3+1] - J[0*3+1]*J[1*3+0]);
453     PetscLogFlops(37.0);
454   }
455   *detJ *= 8.0;
456   ierr   = DMPlexVecRestoreClosure(dm, coordSection, coordinates, e, NULL, &coords);CHKERRQ(ierr);
457   PetscFunctionReturn(0);
458 }
459 
460 #undef __FUNCT__
461 #define __FUNCT__ "DMPlexComputeCellGeometry"
462 /*@C
463   DMPlexComputeCellGeometry - Compute the Jacobian, inverse Jacobian, and Jacobian determinant for a given cell
464 
465   Collective on DM
466 
467   Input Arguments:
468 + dm   - the DM
469 - cell - the cell
470 
471   Output Arguments:
472 + v0   - the translation part of this affine transform
473 . J    - the Jacobian of the transform from the reference element
474 . invJ - the inverse of the Jacobian
475 - detJ - the Jacobian determinant
476 
477   Level: advanced
478 
479   Fortran Notes:
480   Since it returns arrays, this routine is only available in Fortran 90, and you must
481   include petsc.h90 in your code.
482 
483 .seealso: DMPlexGetCoordinateSection(), DMPlexGetCoordinateVec()
484 @*/
485 PetscErrorCode DMPlexComputeCellGeometry(DM dm, PetscInt cell, PetscReal *v0, PetscReal *J, PetscReal *invJ, PetscReal *detJ)
486 {
487   PetscInt       dim, coneSize;
488   PetscErrorCode ierr;
489 
490   PetscFunctionBegin;
491   ierr = DMPlexGetDimension(dm, &dim);CHKERRQ(ierr);
492   ierr = DMPlexGetConeSize(dm, cell, &coneSize);CHKERRQ(ierr);
493   switch (dim) {
494   case 2:
495     switch (coneSize) {
496     case 3:
497       ierr = DMPlexComputeTriangleGeometry_Internal(dm, cell, v0, J, invJ, detJ);CHKERRQ(ierr);
498       break;
499     case 4:
500       ierr = DMPlexComputeRectangleGeometry_Internal(dm, cell, v0, J, invJ, detJ);CHKERRQ(ierr);
501       break;
502     default:
503       SETERRQ2(PetscObjectComm((PetscObject)dm), PETSC_ERR_SUP, "Unsupported number of vertices %D in cell %D for element geometry computation", coneSize, cell);
504     }
505     break;
506   case 3:
507     switch (coneSize) {
508     case 4:
509       ierr = DMPlexComputeTetrahedronGeometry_Internal(dm, cell, v0, J, invJ, detJ);CHKERRQ(ierr);
510       break;
511     case 8:
512       ierr = DMPlexComputeHexahedronGeometry_Internal(dm, cell, v0, J, invJ, detJ);CHKERRQ(ierr);
513       break;
514     default:
515       SETERRQ2(PetscObjectComm((PetscObject)dm), PETSC_ERR_SUP, "Unsupported number of vertices %D in cell %D for element geometry computation", coneSize, cell);
516     }
517     break;
518   default:
519     SETERRQ1(PetscObjectComm((PetscObject)dm), PETSC_ERR_SUP, "Unsupported dimension %D for element geometry computation", dim);
520   }
521   PetscFunctionReturn(0);
522 }
523