xref: /petsc/src/dm/impls/da/dagetelem.c (revision c67aec63658925bcf16afd1ccc5f0cf9c65bc6d4)
1 
2 #include <petsc/private/dmdaimpl.h>     /*I  "petscdmda.h"   I*/
3 
4 #undef __FUNCT__
5 #define __FUNCT__ "DMDAGetElements_1D"
6 static PetscErrorCode DMDAGetElements_1D(DM dm,PetscInt *nel,PetscInt *nen,const PetscInt *e[])
7 {
8   PetscErrorCode ierr;
9   DM_DA          *da = (DM_DA*)dm->data;
10   PetscInt       i,xs,xe,Xs,Xe;
11   PetscInt       cnt=0;
12 
13   PetscFunctionBegin;
14   if (!da->e) {
15     if (!da->s) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_SUP,"Cannot get elements for DMDA with zero stencil width");
16     ierr   = DMDAGetCorners(dm,&xs,0,0,&xe,0,0);CHKERRQ(ierr);
17     ierr   = DMDAGetGhostCorners(dm,&Xs,0,0,&Xe,0,0);CHKERRQ(ierr);
18     xe    += xs; Xe += Xs; if (xs != Xs) xs -= 1;
19     da->ne = 1*(xe - xs - 1);
20     ierr   = PetscMalloc1(1 + 2*da->ne,&da->e);CHKERRQ(ierr);
21     for (i=xs; i<xe-1; i++) {
22       da->e[cnt++] = (i-Xs);
23       da->e[cnt++] = (i-Xs+1);
24     }
25   }
26   *nel = da->ne;
27   *nen = 2;
28   *e   = da->e;
29   PetscFunctionReturn(0);
30 }
31 
32 #undef __FUNCT__
33 #define __FUNCT__ "DMDAGetElements_2D"
34 static PetscErrorCode DMDAGetElements_2D(DM dm,PetscInt *nel,PetscInt *nen,const PetscInt *e[])
35 {
36   PetscErrorCode ierr;
37   DM_DA          *da = (DM_DA*)dm->data;
38   PetscInt       i,xs,xe,Xs,Xe;
39   PetscInt       j,ys,ye,Ys,Ye;
40   PetscInt       cnt=0, cell[4], ns=2, nn=3;
41   PetscInt       c, split[] = {0,1,3,
42                                2,3,1};
43 
44   PetscFunctionBegin;
45   if (!da->e) {
46     if (!da->s) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_SUP,"Cannot get elements for DMDA with zero stencil width");
47     if (da->elementtype == DMDA_ELEMENT_P1) {ns=2; nn=3;}
48     if (da->elementtype == DMDA_ELEMENT_Q1) {ns=1; nn=4;}
49     ierr   = DMDAGetCorners(dm,&xs,&ys,0,&xe,&ye,0);CHKERRQ(ierr);
50     ierr   = DMDAGetGhostCorners(dm,&Xs,&Ys,0,&Xe,&Ye,0);CHKERRQ(ierr);
51     xe    += xs; Xe += Xs; if (xs != Xs) xs -= 1;
52     ye    += ys; Ye += Ys; if (ys != Ys) ys -= 1;
53     da->ne = ns*(xe - xs - 1)*(ye - ys - 1);
54     ierr   = PetscMalloc1(1 + nn*da->ne,&da->e);CHKERRQ(ierr);
55     for (j=ys; j<ye-1; j++) {
56       for (i=xs; i<xe-1; i++) {
57         cell[0] = (i-Xs  ) + (j-Ys  )*(Xe-Xs);
58         cell[1] = (i-Xs+1) + (j-Ys  )*(Xe-Xs);
59         cell[2] = (i-Xs+1) + (j-Ys+1)*(Xe-Xs);
60         cell[3] = (i-Xs  ) + (j-Ys+1)*(Xe-Xs);
61         if (da->elementtype == DMDA_ELEMENT_P1) {
62           for (c=0; c<ns*nn; c++) da->e[cnt++] = cell[split[c]];
63         }
64         if (da->elementtype == DMDA_ELEMENT_Q1) {
65           for (c=0; c<ns*nn; c++) da->e[cnt++] = cell[c];
66         }
67       }
68     }
69   }
70   *nel = da->ne;
71   *nen = nn;
72   *e   = da->e;
73   PetscFunctionReturn(0);
74 }
75 
76 #undef __FUNCT__
77 #define __FUNCT__ "DMDAGetElements_3D"
78 static PetscErrorCode DMDAGetElements_3D(DM dm,PetscInt *nel,PetscInt *nen,const PetscInt *e[])
79 {
80   PetscErrorCode ierr;
81   DM_DA          *da = (DM_DA*)dm->data;
82   PetscInt       i,xs,xe,Xs,Xe;
83   PetscInt       j,ys,ye,Ys,Ye;
84   PetscInt       k,zs,ze,Zs,Ze;
85   PetscInt       cnt=0, cell[8], ns=6, nn=4;
86   PetscInt       c, split[] = {0,1,3,7,
87                                0,1,7,4,
88                                1,2,3,7,
89                                1,2,7,6,
90                                1,4,5,7,
91                                1,5,6,7};
92 
93   PetscFunctionBegin;
94   if (!da->e) {
95     if (!da->s) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_SUP,"Cannot get elements for DMDA with zero stencil width");
96     if (da->elementtype == DMDA_ELEMENT_P1) {ns=6; nn=4;}
97     if (da->elementtype == DMDA_ELEMENT_Q1) {ns=1; nn=8;}
98     ierr   = DMDAGetCorners(dm,&xs,&ys,&zs,&xe,&ye,&ze);CHKERRQ(ierr);
99     ierr   = DMDAGetGhostCorners(dm,&Xs,&Ys,&Zs,&Xe,&Ye,&Ze);CHKERRQ(ierr);
100     xe    += xs; Xe += Xs; if (xs != Xs) xs -= 1;
101     ye    += ys; Ye += Ys; if (ys != Ys) ys -= 1;
102     ze    += zs; Ze += Zs; if (zs != Zs) zs -= 1;
103     da->ne = ns*(xe - xs - 1)*(ye - ys - 1)*(ze - zs - 1);
104     ierr   = PetscMalloc1(1 + nn*da->ne,&da->e);CHKERRQ(ierr);
105     for (k=zs; k<ze-1; k++) {
106       for (j=ys; j<ye-1; j++) {
107         for (i=xs; i<xe-1; i++) {
108           cell[0] = (i-Xs  ) + (j-Ys  )*(Xe-Xs) + (k-Zs  )*(Xe-Xs)*(Ye-Ys);
109           cell[1] = (i-Xs+1) + (j-Ys  )*(Xe-Xs) + (k-Zs  )*(Xe-Xs)*(Ye-Ys);
110           cell[2] = (i-Xs+1) + (j-Ys+1)*(Xe-Xs) + (k-Zs  )*(Xe-Xs)*(Ye-Ys);
111           cell[3] = (i-Xs  ) + (j-Ys+1)*(Xe-Xs) + (k-Zs  )*(Xe-Xs)*(Ye-Ys);
112           cell[4] = (i-Xs  ) + (j-Ys  )*(Xe-Xs) + (k-Zs+1)*(Xe-Xs)*(Ye-Ys);
113           cell[5] = (i-Xs+1) + (j-Ys  )*(Xe-Xs) + (k-Zs+1)*(Xe-Xs)*(Ye-Ys);
114           cell[6] = (i-Xs+1) + (j-Ys+1)*(Xe-Xs) + (k-Zs+1)*(Xe-Xs)*(Ye-Ys);
115           cell[7] = (i-Xs  ) + (j-Ys+1)*(Xe-Xs) + (k-Zs+1)*(Xe-Xs)*(Ye-Ys);
116           if (da->elementtype == DMDA_ELEMENT_P1) {
117             for (c=0; c<ns*nn; c++) da->e[cnt++] = cell[split[c]];
118           }
119           if (da->elementtype == DMDA_ELEMENT_Q1) {
120             for (c=0; c<ns*nn; c++) da->e[cnt++] = cell[c];
121           }
122         }
123       }
124     }
125   }
126   *nel = da->ne;
127   *nen = nn;
128   *e   = da->e;
129   PetscFunctionReturn(0);
130 }
131 
132 /*@C
133       DMDASetElementType - Sets the element type to be returned by DMDAGetElements()
134 
135     Not Collective
136 
137    Input Parameter:
138 .     da - the DMDA object
139 
140    Output Parameters:
141 .     etype - the element type, currently either DMDA_ELEMENT_P1 or ELEMENT_Q1
142 
143    Level: intermediate
144 
145 .seealso: DMDAElementType, DMDAGetElementType(), DMDAGetElements(), DMDARestoreElements()
146 @*/
147 #undef __FUNCT__
148 #define __FUNCT__ "DMDASetElementType"
149 PetscErrorCode  DMDASetElementType(DM da, DMDAElementType etype)
150 {
151   DM_DA          *dd = (DM_DA*)da->data;
152   PetscErrorCode ierr;
153 
154   PetscFunctionBegin;
155   PetscValidHeaderSpecific(da,DM_CLASSID,1);
156   PetscValidLogicalCollectiveEnum(da,etype,2);
157   if (dd->elementtype != etype) {
158     ierr = PetscFree(dd->e);CHKERRQ(ierr);
159 
160     dd->elementtype = etype;
161     dd->ne          = 0;
162     dd->e           = NULL;
163   }
164   PetscFunctionReturn(0);
165 }
166 
167 /*@C
168       DMDAGetElementType - Gets the element type to be returned by DMDAGetElements()
169 
170     Not Collective
171 
172    Input Parameter:
173 .     da - the DMDA object
174 
175    Output Parameters:
176 .     etype - the element type, currently either DMDA_ELEMENT_P1 or ELEMENT_Q1
177 
178    Level: intermediate
179 
180 .seealso: DMDAElementType, DMDASetElementType(), DMDAGetElements(), DMDARestoreElements()
181 @*/
182 #undef __FUNCT__
183 #define __FUNCT__ "DMDAGetElementType"
184 PetscErrorCode  DMDAGetElementType(DM da, DMDAElementType *etype)
185 {
186   DM_DA *dd = (DM_DA*)da->data;
187 
188   PetscFunctionBegin;
189   PetscValidHeaderSpecific(da,DM_CLASSID,1);
190   PetscValidPointer(etype,2);
191   *etype = dd->elementtype;
192   PetscFunctionReturn(0);
193 }
194 
195 /*@C
196       DMDAGetElements - Gets an array containing the indices (in local coordinates)
197                  of all the local elements
198 
199     Not Collective
200 
201    Input Parameter:
202 .     dm - the DM object
203 
204    Output Parameters:
205 +     nel - number of local elements
206 .     nen - number of element nodes
207 -     e - the local indices of the elements' vertices
208 
209    Level: intermediate
210 
211    Notes: Each process uniquely owns a subset of the elements. That is no element is owned by two or more processes.
212 
213           If on each process you integrate over its owned elements and use ADD_VALUES in Vec/MatSetValuesLocal() then you'll obtain the correct result.
214 
215 .seealso: DMDAElementType, DMDASetElementType(), DMDARestoreElements(), VecSetValuesLocal(), MatSetValuesLocal(), DMGlobalToLocalBegin(), DMLocalToGlobalBegin()
216 @*/
217 #undef __FUNCT__
218 #define __FUNCT__ "DMDAGetElements"
219 PetscErrorCode  DMDAGetElements(DM dm,PetscInt *nel,PetscInt *nen,const PetscInt *e[])
220 {
221   PetscInt       dim;
222   PetscErrorCode ierr;
223 
224   PetscFunctionBegin;
225   ierr = DMGetDimension(dm, &dim);CHKERRQ(ierr);
226   if (dim==-1) {
227     *nel = 0; *nen = 0; *e = NULL;
228   } else if (dim==1) {
229     ierr = DMDAGetElements_1D(dm,nel,nen,e);CHKERRQ(ierr);
230   } else if (dim==2) {
231     ierr = DMDAGetElements_2D(dm,nel,nen,e);CHKERRQ(ierr);
232   } else if (dim==3) {
233     ierr = DMDAGetElements_3D(dm,nel,nen,e);CHKERRQ(ierr);
234   } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_CORRUPT,"DMDA dimension not 1, 2, or 3, it is %D\n",dim);
235   PetscFunctionReturn(0);
236 }
237 
238 #undef __FUNCT__
239 #define __FUNCT__ "DMDARestoreElements"
240 /*@C
241       DMDARestoreElements - Restores the array obtained with DMDAGetElements()
242 
243     Not Collective
244 
245    Input Parameter:
246 +     dm - the DM object
247 .     nel - number of local elements
248 .     nen - number of element nodes
249 -     e - the local indices of the elements' vertices
250 
251    Level: intermediate
252 
253    Note: You should not access these values after you have called this routine.
254 
255          This restore signals the DMDA object that you no longer need access to the array information.
256 
257 .seealso: DMDAElementType, DMDASetElementType(), DMDAGetElements()
258 @*/
259 PetscErrorCode  DMDARestoreElements(DM dm,PetscInt *nel,PetscInt *nen,const PetscInt *e[])
260 {
261   PetscFunctionBegin;
262   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
263   PetscValidIntPointer(nel,2);
264   PetscValidIntPointer(nen,3);
265   PetscValidPointer(e,4);
266   *nel = 0;
267   *nen = -1;
268   *e = NULL;
269   PetscFunctionReturn(0);
270 }
271