Date: 2013-09-02T10:07:25+00:00

Actual source code: qeplin_h2.c

      1: /*

      3:    Linearization for gyroscopic QEP, companion form 2.

      5:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      6:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      7:    Copyright (c) 2002-2013, Universitat Politecnica de Valencia, Spain

      9:    This file is part of SLEPc.

     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 <slepc-private/qepimpl.h>         /*I "slepcqep.h" I*/
     26:  #include linearp.h

     28: /*
     29:     Given the quadratic problem (l^2*M + l*C + K)*x = 0 the following
     30:     linearization is employed:

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

     38: PetscErrorCode MatMult_Linear_H2A(Mat A,Vec x,Vec y)
     39: {
     40:   PetscErrorCode    ierr;
     41:   QEP_LINEAR        *ctx;
     42:   const PetscScalar *px;
     43:   PetscScalar       *py;
     44:   PetscInt          m;

     47:   MatShellGetContext(A,(void**)&ctx);
     48:   MatGetLocalSize(ctx->M,&m,NULL);
     49:   VecGetArrayRead(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:   /* y1 = -K*x2 */
     56:   MatMult(ctx->K,ctx->x2,ctx->y1);
     57:   VecScale(ctx->y1,-1.0);
     58:   /* y2 = M*x1 */
     59:   MatMult(ctx->M,ctx->x1,ctx->y2);
     60:   VecScale(ctx->y2,ctx->sfactor*ctx->sfactor);
     61:   VecResetArray(ctx->x1);
     62:   VecResetArray(ctx->x2);
     63:   VecResetArray(ctx->y1);
     64:   VecResetArray(ctx->y2);
     65:   VecRestoreArrayRead(x,&px);
     66:   VecRestoreArray(y,&py);
     67:   return(0);
     68: }

     72: PetscErrorCode MatMult_Linear_H2B(Mat B,Vec x,Vec y)
     73: {
     74:   PetscErrorCode    ierr;
     75:   QEP_LINEAR        *ctx;
     76:   const PetscScalar *px;
     77:   PetscScalar       *py;
     78:   PetscInt          m;

     81:   MatShellGetContext(B,(void**)&ctx);
     82:   MatGetLocalSize(ctx->M,&m,NULL);
     83:   VecGetArrayRead(x,&px);
     84:   VecGetArray(y,&py);
     85:   VecPlaceArray(ctx->x1,px);
     86:   VecPlaceArray(ctx->x2,px+m);
     87:   VecPlaceArray(ctx->y1,py);
     88:   VecPlaceArray(ctx->y2,py+m);
     89:   /* y1 = M*x1 + C*x2 */
     90:   MatMult(ctx->M,ctx->x1,ctx->y1);
     91:   VecScale(ctx->y1,ctx->sfactor*ctx->sfactor);
     92:   MatMult(ctx->C,ctx->x2,ctx->y2);
     93:   VecAXPY(ctx->y1,ctx->sfactor,ctx->y2);
     94:   /* y2 = M*x2 */
     95:   MatMult(ctx->M,ctx->x2,ctx->y2);
     96:   VecScale(ctx->y2,ctx->sfactor*ctx->sfactor);
     97:   VecResetArray(ctx->x1);
     98:   VecResetArray(ctx->x2);
     99:   VecResetArray(ctx->y1);
    100:   VecResetArray(ctx->y2);
    101:   VecRestoreArrayRead(x,&px);
    102:   VecRestoreArray(y,&py);
    103:   return(0);
    104: }

    108: PetscErrorCode MatGetDiagonal_Linear_H2A(Mat A,Vec diag)
    109: {

    113:   VecSet(diag,0.0);
    114:   return(0);
    115: }

    119: PetscErrorCode MatGetDiagonal_Linear_H2B(Mat B,Vec diag)
    120: {
    122:   QEP_LINEAR     *ctx;
    123:   PetscScalar    *pd;
    124:   PetscInt       m;

    127:   MatShellGetContext(B,(void**)&ctx);
    128:   MatGetLocalSize(ctx->M,&m,NULL);
    129:   VecGetArray(diag,&pd);
    130:   VecPlaceArray(ctx->x1,pd);
    131:   VecPlaceArray(ctx->x2,pd+m);
    132:   MatGetDiagonal(ctx->M,ctx->x1);
    133:   VecScale(ctx->x1,ctx->sfactor*ctx->sfactor);
    134:   VecCopy(ctx->x1,ctx->x2);
    135:   VecResetArray(ctx->x1);
    136:   VecResetArray(ctx->x2);
    137:   VecRestoreArray(diag,&pd);
    138:   return(0);
    139: }

    143: PetscErrorCode MatCreateExplicit_Linear_H2A(MPI_Comm comm,QEP_LINEAR *ctx,Mat *A)
    144: {

    148:   SlepcMatTile(0.0,ctx->K,-1.0,ctx->K,ctx->sfactor*ctx->sfactor,ctx->M,0.0,ctx->K,A);
    149:   return(0);
    150: }

    154: PetscErrorCode MatCreateExplicit_Linear_H2B(MPI_Comm comm,QEP_LINEAR *ctx,Mat *B)
    155: {

    159:   SlepcMatTile(ctx->sfactor*ctx->sfactor,ctx->M,ctx->sfactor,ctx->C,0.0,ctx->C,ctx->sfactor*ctx->sfactor,ctx->M,B);
    160:   return(0);
    161: }