| 36 | 
  | 
 * [1]  Meineke, et al., J. Comp. Chem. 26, 252-271 (2005).              | 
| 37 | 
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 * [2]  Fennell & Gezelter, J. Chem. Phys. 124, 234104 (2006).           | 
| 38 | 
  | 
 * [3]  Sun, Lin & Gezelter, J. Chem. Phys. 128, 24107 (2008).           | 
| 39 | 
< | 
 * [4]  Vardeman & Gezelter, in progress (2009).                         | 
| 39 | 
> | 
 * [4]  Kuang & Gezelter,  J. Chem. Phys. 133, 164101 (2010). | 
| 40 | 
> | 
 * [5]  Vardeman, Stocker & Gezelter, J. Chem. Theory Comput. 7, 834 (2011). | 
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 */ | 
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  | 
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/** | 
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       return rotation angle from -PI to PI  | 
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    */ | 
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    inline Real get_rotation_angle() const{ | 
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< | 
      if( w < (Real)0.0 ) | 
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> | 
      if( w() < (Real)0.0 ) | 
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        return 2.0*atan2(-sqrt( x()*x() + y()*y() + z()*z() ), -w() ); | 
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      else | 
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        return 2.0*atan2( sqrt( x()*x() + y()*y() + z()*z() ),  w() ); | 
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                               c.z()); | 
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 | 
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      this->normalize();    // if "from" or "to" not unit, normalize quat | 
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< | 
      w += 1.0f;            // reducing angle to halfangle | 
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< | 
      if( w <= 1e-6 ) {     // angle close to PI | 
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> | 
      w() += 1.0f;            // reducing angle to halfangle | 
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> | 
      if( w() <= 1e-6 ) {     // angle close to PI | 
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        if( ( from.z()*from.z() ) > ( from.x()*from.x() ) ) { | 
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< | 
          this->data_[0] =  w;     | 
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> | 
          this->data_[0] =  w();     | 
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          this->data_[1] =  0.0;       //cross(from , Vector3d(1,0,0)) | 
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          this->data_[2] =  from.z(); | 
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          this->data_[3] = -from.y(); | 
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        } else { | 
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< | 
          this->data_[0] =  w; | 
| 324 | 
> | 
          this->data_[0] =  w(); | 
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          this->data_[1] =  from.y();  //cross(from, Vector3d(0,0,1)) | 
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          this->data_[2] = -from.x(); | 
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          this->data_[3] =  0.0; |