constraint_eqn_091 Subroutine

   subroutine constraint_eqn_091(tmp_cc, tmp_con, tmp_err, tmp_symbol, tmp_units)
      !! Equation for checking if the design point is ECRH ignitable
      !! at lower values for n and B. Or if the design point is ECRH heatable (if ignite==0)
      !! stellarators only (but in principle usable also for tokamaks).
      !! author: J Lion, IPP Greifswald
      !! args : output structure : residual error; constraint value;
      !! residual error in physical units; output string; units string
      !!  powerht_local > powerscaling
      !! #=# physics
      !! #=#=# fecrh_ignition, powerht_local, powerscaling
      !! fecrh_ignition : input real : f-value for constraint powerht_local > powerscaling
      !! max_gyrotron_frequency : input real :  Max. av. gyrotron frequency
      !! te0_ecrh_achievable : input real : Max. achievable electron temperature at ignition point
      use constraint_variables, only: fecrh_ignition
      use stellarator_variables, only: max_gyrotron_frequency, te0_ecrh_achievable, powerscaling_constraint, powerht_constraint
      use physics_variables, only: ignite
      use current_drive_variables, only: pheat
      implicit none
      real(dp), intent(out) :: tmp_cc
      real(dp), intent(out) :: tmp_con
      real(dp), intent(out) :: tmp_err
      character(len=1), intent(out) :: tmp_symbol
      character(len=10), intent(out) :: tmp_units

      ! Achievable ECRH te needs to be larger than needed te for igntion
      if(ignite==0) then
         tmp_cc = 1.0D0 - fecrh_ignition* (powerht_constraint+pheat)/powerscaling_constraint
      else
         tmp_cc = 1.0D0 - fecrh_ignition* powerht_constraint/powerscaling_constraint
      endif

      tmp_con = powerscaling_constraint * (1.0D0 - tmp_cc)
      tmp_err = powerht_constraint * tmp_cc
      tmp_symbol = '<'
      tmp_units = 'MW'
   end subroutine constraint_eqn_091