anchor.diff:  !>  \author                date              version
   !>  X.Yuan(Advancesoft)    2010/10/06        original
   !>  X.Yuan                 2012/09/18        add trs function(WLF, ARRHENIUS)
  -!>
  +!>  X.Yuan                 2016/09/26        abnormal processing in TRS
   !
   !======================================================================!
   module mViscoElastic
  
positive.code: !-------------------------------------------------------------------------------
  !> This subroutine provides to update stress for viscoelastic material
    subroutine UpdateViscoelastic(matl, sectType, eps, sig, vsig, dt, temp, tempn)
        TYPE( tMaterial ), INTENT(IN)   :: matl      !< material properties
        INTEGER, INTENT(IN)             :: sectType  !< not used currently
        REAL(KIND=kreal), INTENT(IN)    :: eps(6)    !< strain after this step
  
negative.code:           PP = outa(2)
          endif
          if( matl%mtype>VISCOELASTIC ) ddt=trsinc(temp,tempn, matl%mtype, matl%variables)*dt
          if( ddt<=0.d0 ) then
             call calElasticMatrix( matl, sectType, D, temp  )
             sig = matmul( D(:,:), eps(:) )
             vsig = 0.d0
             return
          endif
        else
          EE = matl%variables(M_YOUNGS)
          PP = matl%variables(M_POISSON)
  