sillyModifiedGramSchmidt.hpp

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// ***********************************************************************
// 
//    Thyra: Interfaces and Support for Abstract Numerical Algorithms
//                 Copyright (2004) Sandia Corporation
// 
// Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
// license for use of this work by or on behalf of the U.S. Government.
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// This library is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as
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// Lesser General Public License for more details.
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// Questions? Contact Michael A. Heroux (maherou@sandia.gov) 
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#ifndef THYRA_SILLY_MODIFIED_GRAM_SHMIDT_HPP
#define THYRA_SILLY_MODIFIED_GRAM_SHMIDT_HPP

#include "Thyra_MultiVectorBase.hpp"
#include "Thyra_MultiVectorStdOps.hpp"
#include "Thyra_VectorStdOps.hpp"
#include "Thyra_DetachedMultiVectorView.hpp"

template<class Scalar>
void sillyModifiedGramSchmidt(
  Thyra::MultiVectorBase<Scalar> *V_inout
  ,Teuchos::RCP<Thyra::MultiVectorBase<Scalar> > *R_out
  )
{
  typedef Teuchos::ScalarTraits<Scalar> ST;
  TEST_FOR_EXCEPT(V_inout==NULL);
  Thyra::MultiVectorBase<Scalar> &V = *V_inout;
  const int n = V.domain()->dim();
  *R_out = Thyra::createMembers(V.domain(),n);
  //Thyra::assign(&*(*R_out),ST::zero());
  Thyra::DetachedMultiVectorView<Scalar> R(*(*R_out));
  for( int k = 0; k < n; ++k ) {
    R(k,k) = Thyra::norm(*V.col(k));
    Thyra::scale(Scalar(ST::one()/R(k,k)),&*V.col(k));
    for( int j = k+1; j < n; ++j ) {
      R(k,j) = Thyra::scalarProd(*V.col(k),*V.col(j));
      Thyra::update( Scalar(-R(k,j)), *V.col(k), &*V.col(j) );
    }
  }

} // end sillyModifiedGramSchmidt

#endif // THYRA_SILLY_MODIFIED_GRAM_SHMIDT_HPP

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