xref: /petsc/src/dm/impls/da/dagetelem.c (revision 9192b5d6335036e5b0385ec2ea1d63cdfcc779f2)
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   DM_DA          *dd = (DM_DA*)dm->data;
224 
225   PetscFunctionBegin;
226   if (dd->stencil_type == DMDA_STENCIL_STAR) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_SUP,"DMDAGetElement() requires you use a stencil type of DMDA_STENCIL_BOX");
227   ierr = DMGetDimension(dm, &dim);CHKERRQ(ierr);
228   if (dim==-1) {
229     *nel = 0; *nen = 0; *e = NULL;
230   } else if (dim==1) {
231     ierr = DMDAGetElements_1D(dm,nel,nen,e);CHKERRQ(ierr);
232   } else if (dim==2) {
233     ierr = DMDAGetElements_2D(dm,nel,nen,e);CHKERRQ(ierr);
234   } else if (dim==3) {
235     ierr = DMDAGetElements_3D(dm,nel,nen,e);CHKERRQ(ierr);
236   } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_CORRUPT,"DMDA dimension not 1, 2, or 3, it is %D\n",dim);
237   PetscFunctionReturn(0);
238 }
239 
240 #undef __FUNCT__
241 #define __FUNCT__ "DMDARestoreElements"
242 /*@C
243       DMDARestoreElements - Restores the array obtained with DMDAGetElements()
244 
245     Not Collective
246 
247    Input Parameter:
248 +     dm - the DM object
249 .     nel - number of local elements
250 .     nen - number of element nodes
251 -     e - the local indices of the elements' vertices
252 
253    Level: intermediate
254 
255    Note: You should not access these values after you have called this routine.
256 
257          This restore signals the DMDA object that you no longer need access to the array information.
258 
259 .seealso: DMDAElementType, DMDASetElementType(), DMDAGetElements()
260 @*/
261 PetscErrorCode  DMDARestoreElements(DM dm,PetscInt *nel,PetscInt *nen,const PetscInt *e[])
262 {
263   PetscFunctionBegin;
264   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
265   PetscValidIntPointer(nel,2);
266   PetscValidIntPointer(nen,3);
267   PetscValidPointer(e,4);
268   *nel = 0;
269   *nen = -1;
270   *e = NULL;
271   PetscFunctionReturn(0);
272 }
273