Actual source code: mfnsolve.c

slepc-3.7.1 2016-05-27
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  1: /*
  2:       MFN routines related to the solution process.

  4:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  5:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  6:    Copyright (c) 2002-2016, Universitat Politecnica de Valencia, Spain

  8:    This file is part of SLEPc.

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

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

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

 24: #include <slepc/private/mfnimpl.h>   /*I "slepcmfn.h" I*/

 28: /*@
 29:    MFNSolve - Solves the matrix function problem. Given a vector b, the
 30:    vector x = f(A)*b is returned.

 32:    Collective on MFN

 34:    Input Parameters:
 35: +  mfn - matrix function context obtained from MFNCreate()
 36: -  b   - the right hand side vector

 38:    Output Parameter:
 39: .  x   - the solution (this may be the same vector as b, then b will be
 40:          overwritten with the answer)

 42:    Options Database Keys:
 43: +  -mfn_view - print information about the solver used
 44: .  -mfn_view_mat binary - save the matrix to the default binary viewer
 45: .  -mfn_view_rhs binary - save right hand side vector to the default binary viewer
 46: .  -mfn_view_solution binary - save computed solution vector to the default binary viewer
 47: -  -mfn_converged_reason - print reason for convergence, and number of iterations

 49:    Notes:
 50:    The matrix A is specified with MFNSetOperator().
 51:    The function f is specified with MFNSetFN().

 53:    Level: beginner

 55: .seealso: MFNCreate(), MFNSetUp(), MFNDestroy(), MFNSetTolerances(),
 56:           MFNSetOperator(), MFNSetFN()
 57: @*/
 58: PetscErrorCode MFNSolve(MFN mfn,Vec b,Vec x)
 59: {

 68:   VecLocked(x,3);

 70:   /* call setup */
 71:   MFNSetUp(mfn);
 72:   mfn->its = 0;

 74:   MFNViewFromOptions(mfn,NULL,"-mfn_view_pre");

 76:   /* check nonzero right-hand side */
 77:   VecNorm(b,NORM_2,&mfn->bnorm);
 78:   if (!mfn->bnorm) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Cannot pass a zero b vector to MFNSolve()");

 80:   /* call solver */
 81:   PetscLogEventBegin(MFN_Solve,mfn,b,x,0);
 82:   VecLockPush(b);
 83:   (*mfn->ops->solve)(mfn,b,x);
 84:   VecLockPop(b);
 85:   PetscLogEventEnd(MFN_Solve,mfn,b,x,0);

 87:   if (!mfn->reason) SETERRQ(PetscObjectComm((PetscObject)mfn),PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");

 89:   if (mfn->errorifnotconverged && mfn->reason < 0) SETERRQ(PetscObjectComm((PetscObject)mfn),PETSC_ERR_NOT_CONVERGED,"MFNSolve has not converged");

 91:   /* various viewers */
 92:   MFNViewFromOptions(mfn,NULL,"-mfn_view");
 93:   MFNReasonViewFromOptions(mfn);
 94:   MatViewFromOptions(mfn->A,(PetscObject)mfn,"-mfn_view_mat");
 95:   VecViewFromOptions(b,(PetscObject)mfn,"-mfn_view_rhs");
 96:   VecViewFromOptions(x,(PetscObject)mfn,"-mfn_view_solution");
 97:   return(0);
 98: }

102: /*@
103:    MFNGetIterationNumber - Gets the current iteration number. If the
104:    call to MFNSolve() is complete, then it returns the number of iterations
105:    carried out by the solution method.

107:    Not Collective

109:    Input Parameter:
110: .  mfn - the matrix function context

112:    Output Parameter:
113: .  its - number of iterations

115:    Level: intermediate

117:    Note:
118:    During the i-th iteration this call returns i-1. If MFNSolve() is
119:    complete, then parameter "its" contains either the iteration number at
120:    which convergence was successfully reached, or failure was detected.
121:    Call MFNGetConvergedReason() to determine if the solver converged or
122:    failed and why.

124: .seealso: MFNGetConvergedReason(), MFNSetTolerances()
125: @*/
126: PetscErrorCode MFNGetIterationNumber(MFN mfn,PetscInt *its)
127: {
131:   *its = mfn->its;
132:   return(0);
133: }

137: /*@
138:    MFNGetConvergedReason - Gets the reason why the MFNSolve() iteration was
139:    stopped.

141:    Not Collective

143:    Input Parameter:
144: .  mfn - the matrix function context

146:    Output Parameter:
147: .  reason - negative value indicates diverged, positive value converged

149:    Notes:

151:    Possible values for reason are
152: +  MFN_CONVERGED_TOL - converged up to tolerance
153: .  MFN_CONVERGED_ITS - solver completed the requested number of steps
154: .  MFN_DIVERGED_ITS - required more than max_it iterations to reach convergence
155: -  MFN_DIVERGED_BREAKDOWN - generic breakdown in method

157:    Can only be called after the call to MFNSolve() is complete.

159:    Basic solvers (e.g. unrestarted Krylov iterations) cannot determine if the
160:    computation is accurate up to the requested tolerance. In that case, the
161:    converged reason is set to MFN_CONVERGED_ITS if the requested number of steps
162:    (for instance, the ncv value in unrestarted Krylov methods) have been
163:    completed successfully.

165:    Level: intermediate

167: .seealso: MFNSetTolerances(), MFNSolve(), MFNConvergedReason, MFNSetErrorIfNotConverged()
168: @*/
169: PetscErrorCode MFNGetConvergedReason(MFN mfn,MFNConvergedReason *reason)
170: {
174:   *reason = mfn->reason;
175:   return(0);
176: }