1. Dec 23, 2000:

_S_ = sqrt( 4. * ( du_dx * du_dx + dv_dy * dv_dy + dw_dz * dw_dz )
		  + 2. * ( S12   * S12   + S13   * S13   + S23   * S23 ) );
		  
   was replaced by		  

_S_ = sqrt( 2. * ( du_dx * du_dx + dv_dy * dv_dy + dw_dz * dw_dz )
		      +  ( S12   * S12   + S13   * S13   + S23   * S23 ) );
		  
/*
  |S| = sqrt( 2 * Sij * Sij ),  
  where Sij = 0.5 * ( dui/dxj + duj/dxi ) 
*/
  
2. What else?....
