C++ MsqHessian::scale方法代码示例

bool PMeanPTemplate::evaluate_with_Hessian( EvalType type, 
                                        PatchData& pd,
                                        double& value_out,
                                        std::vector<Vector3D>& grad_out,
                                        MsqHessian& Hessian_out,
                                        MsqError& err )
{
  QualityMetric* qm = get_quality_metric();
  qm->get_evaluations( pd, qmHandles, OF_FREE_EVALS_ONLY, err );  MSQ_ERRFALSE(err);
  
    // zero gradient and hessian
  grad_out.clear();
  grad_out.resize( pd.num_free_vertices(), 0.0 );
  Hessian_out.zero_out();
  
    // calculate OF value and gradient for just the patch
  std::vector<size_t>::const_iterator i;
  size_t j, k, n;
  double value, working_sum = 0.0;
  const double f1 = qm->get_negate_flag() * mPower.value();
  const double f2 = f1 * (mPower.value() - 1);
  Matrix3D m;
  for (i = qmHandles.begin(); i != qmHandles.end(); ++i)
  {
    bool result = qm->evaluate_with_Hessian( pd, *i, value, mIndices, mGradient, mHessian, err );
    if (MSQ_CHKERR(err) || !result)
      return false;
    if (fabs(value) < DBL_EPSILON)
      continue;
    
    const size_t nfree = mIndices.size();
    n = 0;
    if (mPower.value() == 1.0) {
      working_sum += mPower.raise( value );
      for (j = 0; j < nfree; ++j) {
        mGradient[j] *= f1;
        grad_out[mIndices[j]] += mGradient[j];
        for (k = j; k < nfree; ++k) {
          mHessian[n] *= f1;
          Hessian_out.add( mIndices[j], mIndices[k], mHessian[n], err );  MSQ_ERRFALSE(err);
          ++n;
        }
     }
    }
    else {
      const double r2 = mPowerMinus2.raise( value );
      const double r1 = r2 * value;
      working_sum += r1 * value;
      const double hf = f2 * r2;
      const double gf = f1 * r1;
      for (j = 0; j < nfree; ++j) {
        for (k = j; k < nfree; ++k) {
          m.outer_product( mGradient[j], mGradient[k] );
          m *= hf;
          mHessian[n] *= gf;
          m += mHessian[n];
          Hessian_out.add( mIndices[j], mIndices[k], m, err );  MSQ_ERRFALSE(err);
          ++n;
        }
      }
      for (j = 0; j < nfree; ++j) {
        mGradient[j] *= gf;
        grad_out[mIndices[j]] += mGradient[j];
      }
    }
  }
  
    // get overall OF value, update member data, etc.
  size_t global_count;
  value_out = qm->get_negate_flag() 
            * get_value( working_sum, qmHandles.size(), type, global_count );
  const double inv_n = 1.0 / global_count;
  std::vector<Vector3D>::iterator g;
  for (g = grad_out.begin(); g != grad_out.end(); ++g)
    *g *= inv_n;
  Hessian_out.scale( inv_n );
  return true;
}

//.........这里部分代码省略.........
  grad.resize( pd.num_free_vertices(), 0.0 );
  hessian.zero_out();
  
  double QM_val, QM_pow = 1.0;
  double fac1, fac2;
  Matrix3D elem_outer_product;
  bool qm_bool;
  size_t i, j, n;
  short p;
   
  // Loops over all elements in the patch.
  OF_val = 0.0;
  std::vector<size_t>::const_iterator k;
  for (k = qmHandles.begin(); k != qmHandles.end(); ++k)
  {
    // Computes \nabla^2 Q(e). Only the free vertices will have non-zero entries. 
    qm_bool = qm->evaluate_with_Hessian( pd, *k, QM_val, mIndices, mGradient, mHessian, err );
    if (MSQ_CHKERR(err) || !qm_bool) 
      return false;
    QM_val = fabs(QM_val);

    // **** Computes Hessian ****
    const size_t nve = mIndices.size();
    if (pVal == 1) {
      QM_pow = 1.0;
      n=0;
      for (i=0; i<nve; ++i) {
        for (j=i; j<nve; ++j) {
            //negate if necessary
          mHessian[n] *= negate_flag;
          hessian.add( mIndices[i], mIndices[j], mHessian[n], err ); MSQ_ERRFALSE(err);
          ++n;
        }
      }
      fac1 = 1;
    }
    else if (pVal >= 2) {
       // Computes the coefficients:
      QM_pow = 1.0;
      for (p=0; p<pVal-2; ++p)
        QM_pow *= QM_val;
      // 1 - computes p(p-1)Q(e)^{p-2}
      fac2 = pVal* (pVal-1) * QM_pow;
      // 2 - computes  pQ(e)^{p-1}
      QM_pow *= QM_val;
      fac1 = pVal * QM_pow;

        //fac1 *= qm->get_negate_flag();
        //fac2 *= qm->get_negate_flag();

      n=0;
      for (i=0; i<nve; ++i) {
        for (j=i; j<nve; ++j) {
          elem_outer_product.outer_product(mGradient[i], mGradient[j]);
          elem_outer_product *= fac2;
          mHessian[n] *= fac1;
          mHessian[n] += elem_outer_product;
          mHessian[n] *= negate_flag;
          hessian.add( mIndices[i], mIndices[j], mHessian[n], err ); MSQ_ERRFALSE(err);
          ++n;
        }
      }
    } else {
      MSQ_SETERR(err)(" invalid P value.", MsqError::INVALID_STATE);
      return false;
    }


    // **** Computes Gradient ****

    // For each vertex in the element ... 
    for (i=0; i<nve; ++i) {
      // ... computes p*q^{p-1}*grad(q) ...
      mGradient[i] *= fac1*negate_flag;
      // ... and accumulates it in the objective function gradient.
        //also scale the gradient by the scaling factor
      assert (mIndices[i] < pd.num_free_vertices());
      grad[mIndices[i]] += mGradient[i];
    }

    // **** computes Objective Function value \sum_{i=1}^{N_e} |q_i|^P ****
    OF_val += QM_pow * QM_val;
  }

  size_t global_count;
  OF_val = negate_flag
         * get_value( OF_val, qmHandles.size(), type, global_count, err );
//  if (!global_count)
//    return false;  // invalid mesh

  if (dividingByN && global_count) {
    const double inv_n = 1.0 / global_count;
    std::vector<Vector3D>::iterator g;
    for (g = grad.begin(); g != grad.end(); ++g)
      *g *= inv_n;
    hessian.scale( inv_n );
  }
  
  return true;
}