Actual source code: qeplin_s1.c

  1: /*                       

  3:    Linearization for Hermitian QEP, companion form 1.

  5:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  6:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  7:    Copyright (c) 2002-2010, Universidad Politecnica de Valencia, Spain

  9:    This file is part of SLEPc.
 10:       
 11:    SLEPc is free software: you can redistribute it and/or modify it under  the
 12:    terms of version 3 of the GNU Lesser General Public License as published by
 13:    the Free Software Foundation.

 15:    SLEPc  is  distributed in the hope that it will be useful, but WITHOUT  ANY 
 16:    WARRANTY;  without even the implied warranty of MERCHANTABILITY or  FITNESS 
 17:    FOR  A  PARTICULAR PURPOSE. See the GNU Lesser General Public  License  for 
 18:    more details.

 20:    You  should have received a copy of the GNU Lesser General  Public  License
 21:    along with SLEPc. If not, see <http://www.gnu.org/licenses/>.
 22:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 23: */

 25:  #include private/qepimpl.h
 26:  #include slepceps.h
 27:  #include linearp.h

 29: /*
 30:     Given the quadratic problem (l^2*M + l*C + K)*x = 0 the following
 31:     linearization is employed:

 33:       A*z = l*B*z   where   A = [  0  -K ]     B = [-K  0 ]     z = [  x  ]
 34:                                 [ -K  -C ]         [ 0  M ]         [ l*x ]
 35:  */

 39: PetscErrorCode MatMult_QEPLINEAR_S1A(Mat A,Vec x,Vec y)
 40: {
 42:   QEP_LINEAR     *ctx;
 43:   PetscScalar    *px,*py;
 44:   PetscInt       m;
 45: 
 47:   MatShellGetContext(A,(void**)&ctx);
 48:   MatGetLocalSize(ctx->M,&m,PETSC_NULL);
 49:   VecGetArray(x,&px);
 50:   VecGetArray(y,&py);
 51:   VecPlaceArray(ctx->x1,px);
 52:   VecPlaceArray(ctx->x2,px+m);
 53:   VecPlaceArray(ctx->y1,py);
 54:   VecPlaceArray(ctx->y2,py+m);
 55:   /* y2 = -(K*x1 + C*x2) */
 56:   MatMult(ctx->K,ctx->x1,ctx->y2);
 57:   VecScale(ctx->y2,-1.0);
 58:   MatMult(ctx->C,ctx->x2,ctx->y1);
 59:   VecAXPY(ctx->y2,-ctx->sfactor,ctx->y1);
 60:   /* y1 = -K*x2 */
 61:   MatMult(ctx->K,ctx->x2,ctx->y1);
 62:   VecScale(ctx->y1,-1.0);
 63:   VecResetArray(ctx->x1);
 64:   VecResetArray(ctx->x2);
 65:   VecResetArray(ctx->y1);
 66:   VecResetArray(ctx->y2);
 67:   VecRestoreArray(x,&px);
 68:   VecRestoreArray(y,&py);
 69:   return(0);
 70: }

 74: PetscErrorCode MatMult_QEPLINEAR_S1B(Mat B,Vec x,Vec y)
 75: {
 77:   QEP_LINEAR     *ctx;
 78:   PetscScalar    *px,*py;
 79:   PetscInt       m;
 80: 
 82:   MatShellGetContext(B,(void**)&ctx);
 83:   MatGetLocalSize(ctx->M,&m,PETSC_NULL);
 84:   VecGetArray(x,&px);
 85:   VecGetArray(y,&py);
 86:   VecPlaceArray(ctx->x1,px);
 87:   VecPlaceArray(ctx->x2,px+m);
 88:   VecPlaceArray(ctx->y1,py);
 89:   VecPlaceArray(ctx->y2,py+m);
 90:   /* y1 = -K*x1 */
 91:   MatMult(ctx->K,ctx->x1,ctx->y1);
 92:   VecScale(ctx->y1,-1.0);
 93:   /* y2 = M*x2 */
 94:   MatMult(ctx->M,ctx->x2,ctx->y2);
 95:   VecScale(ctx->y2,ctx->sfactor*ctx->sfactor);
 96:   VecResetArray(ctx->x1);
 97:   VecResetArray(ctx->x2);
 98:   VecResetArray(ctx->y1);
 99:   VecResetArray(ctx->y2);
100:   VecRestoreArray(x,&px);
101:   VecRestoreArray(y,&py);
102:   return(0);
103: }

107: PetscErrorCode MatGetDiagonal_QEPLINEAR_S1A(Mat A,Vec diag)
108: {
110:   QEP_LINEAR     *ctx;
111:   PetscScalar    *pd;
112:   PetscInt       m;
113: 
115:   MatShellGetContext(A,(void**)&ctx);
116:   MatGetLocalSize(ctx->M,&m,PETSC_NULL);
117:   VecGetArray(diag,&pd);
118:   VecPlaceArray(ctx->x1,pd);
119:   VecPlaceArray(ctx->x2,pd+m);
120:   VecSet(ctx->x1,0.0);
121:   MatGetDiagonal(ctx->C,ctx->x2);
122:   VecScale(ctx->x2,-ctx->sfactor);
123:   VecResetArray(ctx->x1);
124:   VecResetArray(ctx->x2);
125:   VecRestoreArray(diag,&pd);
126:   return(0);
127: }

131: PetscErrorCode MatGetDiagonal_QEPLINEAR_S1B(Mat B,Vec diag)
132: {
134:   QEP_LINEAR     *ctx;
135:   PetscScalar    *pd;
136:   PetscInt       m;
137: 
139:   MatShellGetContext(B,(void**)&ctx);
140:   MatGetLocalSize(ctx->M,&m,PETSC_NULL);
141:   VecGetArray(diag,&pd);
142:   VecPlaceArray(ctx->x1,pd);
143:   VecPlaceArray(ctx->x2,pd+m);
144:   MatGetDiagonal(ctx->K,ctx->x1);
145:   VecScale(ctx->x1,-1.0);
146:   MatGetDiagonal(ctx->M,ctx->x2);
147:   VecScale(ctx->x2,ctx->sfactor*ctx->sfactor);
148:   VecResetArray(ctx->x1);
149:   VecResetArray(ctx->x2);
150:   VecRestoreArray(diag,&pd);
151:   return(0);
152: }

156: PetscErrorCode MatCreateExplicit_QEPLINEAR_S1A(MPI_Comm comm,QEP_LINEAR *ctx,Mat *A)
157: {
159:   PetscInt       M,N,m,n,i,j,row,start,end,ncols,*pos;
160:   PetscScalar    *svals;
161:   const PetscInt    *cols;
162:   const PetscScalar *vals;
163: 
165:   MatGetSize(ctx->M,&M,&N);
166:   MatGetLocalSize(ctx->M,&m,&n);
167:   MatCreate(comm,A);
168:   MatSetSizes(*A,m+n,m+n,M+N,M+N);
169:   MatSetFromOptions(*A);
170:   PetscMalloc(sizeof(PetscInt)*n,&pos);
171:   PetscMalloc(sizeof(PetscScalar)*n,&svals);
172:   MatGetOwnershipRange(ctx->M,&start,&end);
173:   for (i=start;i<end;i++) {
174:     row = i + M;
175:     MatGetRow(ctx->K,i,&ncols,&cols,&vals);
176:     MatSetValues(*A,1,&row,ncols,cols,vals,INSERT_VALUES);
177:     for (j=0;j<ncols;j++)
178:       pos[j] = cols[j] + M;
179:     MatSetValues(*A,1,&i,ncols,pos,vals,INSERT_VALUES);
180:     MatRestoreRow(ctx->K,i,&ncols,&cols,&vals);
181:     MatGetRow(ctx->C,i,&ncols,&cols,&vals);
182:     for (j=0;j<ncols;j++) {
183:       pos[j] = cols[j] + M;
184:       svals[j] = vals[j]*ctx->sfactor;
185:     }
186:     MatSetValues(*A,1,&row,ncols,pos,svals,INSERT_VALUES);
187:     MatRestoreRow(ctx->C,i,&ncols,&cols,&vals);
188:   }
189:   PetscFree(pos);
190:   PetscFree(svals);
191:   MatAssemblyBegin(*A,MAT_FINAL_ASSEMBLY);
192:   MatAssemblyEnd(*A,MAT_FINAL_ASSEMBLY);
193:   MatScale(*A,-1.0);
194:   return(0);
195: }

199: PetscErrorCode MatCreateExplicit_QEPLINEAR_S1B(MPI_Comm comm,QEP_LINEAR *ctx,Mat *B)
200: {
202:   PetscInt       M,N,m,n,i,j,row,start,end,ncols,*pos;
203:   PetscScalar    *svals;
204:   const PetscInt    *cols;
205:   const PetscScalar *vals;
206: 
208:   MatGetSize(ctx->M,&M,&N);
209:   MatGetLocalSize(ctx->M,&m,&n);
210:   MatCreate(comm,B);
211:   MatSetSizes(*B,m+n,m+n,M+N,M+N);
212:   MatSetFromOptions(*B);
213:   PetscMalloc(sizeof(PetscInt)*n,&pos);
214:   PetscMalloc(sizeof(PetscScalar)*n,&svals);
215:   MatGetOwnershipRange(ctx->M,&start,&end);
216:   for (i=start;i<end;i++) {
217:     MatGetRow(ctx->K,i,&ncols,&cols,&vals);
218:     MatSetValues(*B,1,&i,ncols,cols,vals,INSERT_VALUES);
219:     MatRestoreRow(ctx->K,i,&ncols,&cols,&vals);
220:   }
221:   MatAssemblyBegin(*B,MAT_FINAL_ASSEMBLY);
222:   MatAssemblyEnd(*B,MAT_FINAL_ASSEMBLY);
223:   MatScale(*B,-1.0);
224:   for (i=start;i<end;i++) {
225:     row = i + M;
226:     MatGetRow(ctx->M,i,&ncols,&cols,&vals);
227:     for (j=0;j<ncols;j++) {
228:       pos[j] = cols[j] + M;
229:       svals[j] = vals[j]*ctx->sfactor*ctx->sfactor;
230:     }
231:     MatSetValues(*B,1,&row,ncols,pos,svals,INSERT_VALUES);
232:     MatRestoreRow(ctx->M,i,&ncols,&cols,&vals);
233:   }
234:   MatAssemblyBegin(*B,MAT_FINAL_ASSEMBLY);
235:   MatAssemblyEnd(*B,MAT_FINAL_ASSEMBLY);
236:   PetscFree(pos);
237:   PetscFree(svals);
238:   return(0);
239: }