MODULE FF_Cost_Functions
      USE Precision
      USE Error_Handling
      USE System_Monitors
      USE Network_Data_Structures
      USE Network_Data_Types
      USE FF_Cost_Parameters
      IMPLICIT NONE
      PUBLIC::FFElementalCosts
      PRIVATE
      
      INTEGER,SAVE,PUBLIC::ff_elemental_costs_timer=-1
      
      CONTAINS
      
      
      SUBROUTINE FFElementalCosts(cost_function,arguments_status,tolerance,&
      arcs_indices,arcs_flows,arcs_voltages,arcs_resistances,arcs_costs)
      USE Precision
      USE Network_Data_Types
      TYPE(Network_SC_Cost),INTENT(INOUT),OPTIONAL::cost_function
      CHARACTER(LEN=4),INTENT(IN)::arguments_status
      REAL(KIND=r_wp),INTENT(IN)::tolerance
      INTEGER(KIND=i_wp),DIMENSION(2),INTENT(IN)::arcs_indices
      REAL(KIND=r_wp),DIMENSION(arcs_indices(1):),INTENT(INOUT),OPTIONAL::&
      arcs_flows,arcs_voltages,arcs_resistances,arcs_costs
      
      LOGICAL::known_flow,known_voltage
      CHARACTER::status
      INTEGER(KIND=i_wp)::arc
      REAL(KIND=r_wp)::eps,temp
      eps=MAX(EPSILON(1.0_r_wp),tolerance)
      
      CALL StartTimer(ff_elemental_costs_timer)
      
      
      
      
      status=arguments_status(1:1)
      known_flow=(status=='F')
      IF((.NOT.known_flow).AND.status/='D')THEN
      DO arc=arcs_indices(1),arcs_indices(2)
      arcs_flows(arc)=SIGN(1.0_r_wp,arcs_voltages(arc))*&
      (2*ABS(arcs_voltages(arc)))*(ABS(arcs_voltages(arc))+arcs_cost_parameters(3,arc)*arcs_cost_parameters(4,arc))/(arcs_cost_par&
     &ameters(3,arc)*((2*ABS(arcs_voltages(arc)))+arcs_cost_parameters(3,arc)*(arcs_cost_parameters(4,arc)-arcs_cost_parameters(1,&
     &arc))))
      END DO
      known_flow=.TRUE.
      END IF
      
      
      status=arguments_status(2:2)
      known_voltage=(status=='F')
      IF((.NOT.known_voltage).AND.status/='D')THEN
      DO arc=arcs_indices(1),arcs_indices(2)
      arcs_voltages(arc)=SIGN(1.0_r_wp,arcs_flows(arc))*0.5_r_wp*arcs_cost_parameters(3,arc)*(SQRT((ABS(arcs_flows(arc))-arcs_cost&
     &_parameters(1,arc))**2+arcs_cost_parameters(2,arc)**2)+ABS(arcs_flows(arc))-arcs_cost_parameters(4,arc))
      END DO
      known_voltage=.TRUE.
      END IF
      
      
      status=arguments_status(3:3)
      IF(status/='F'.AND.status/='D')THEN
      
      IF(arguments_status(1:1)=='F')THEN
      DO arc=arcs_indices(1),arcs_indices(2)
      arcs_resistances(arc)=0.5_r_wp*arcs_cost_parameters(3,arc)*(1.0_r_wp+(ABS(arcs_flows(arc))-arcs_cost_parameters(1,arc))/SQRT&
     &((ABS(arcs_flows(arc))-arcs_cost_parameters(1,arc))**2+arcs_cost_parameters(2,arc)**2))
      END DO
      ELSE IF(arguments_status(2:2)=='F')THEN
      DO arc=arcs_indices(1),arcs_indices(2)
      arcs_resistances(arc)=arcs_cost_parameters(3,arc)/(1.0_r_wp+(arcs_cost_parameters(2,arc)/((2*ABS(arcs_voltages(arc)))/arcs_c&
     &ost_parameters(3,arc)-arcs_cost_parameters(1,arc)+arcs_cost_parameters(4,arc)))**2)
      END DO
      ELSE
      arcs_resistances=0.0_r_wp
      END IF
      END IF
      
      
      status=arguments_status(4:4)
      IF(status/='F'.AND.status/='D')THEN
      IF(known_flow)THEN
      DO arc=arcs_indices(1),arcs_indices(2)
      arcs_costs(arc)=0.25_r_wp*arcs_cost_parameters(3,arc)*(ABS(arcs_flows(arc))**2+(arcs_cost_parameters(1,arc)-2*ABS(arcs_flows&
     &(arc)))*arcs_cost_parameters(4,arc)+(ABS(arcs_flows(arc))-arcs_cost_parameters(1,arc))*SQRT((ABS(arcs_flows(arc))-arcs_cost_&
     &parameters(1,arc))**2+arcs_cost_parameters(2,arc)**2)+&
      arcs_cost_parameters(2,arc)**2*(LOG(ABS(arcs_flows(arc))-arcs_cost_parameters(1,arc)+SQRT((ABS(arcs_flows(arc))-arcs_cost_pa&
     &rameters(1,arc))**2+arcs_cost_parameters(2,arc)**2))-LOG(arcs_cost_parameters(4,arc)-arcs_cost_parameters(1,arc))))
      END DO
      ELSE IF(known_voltage)THEN
      DO arc=arcs_indices(1),arcs_indices(2)
      temp=(2*ABS(arcs_voltages(arc)))*(ABS(arcs_voltages(arc))+arcs_cost_parameters(3,arc)*arcs_cost_parameters(4,arc))/(arcs_cos&
     &t_parameters(3,arc)*((2*ABS(arcs_voltages(arc)))+arcs_cost_parameters(3,arc)*(arcs_cost_parameters(4,arc)-arcs_cost_paramete&
     &rs(1,arc))))
      arcs_costs(arc)=0.25_r_wp*arcs_cost_parameters(3,arc)*(temp**2+(arcs_cost_parameters(1,arc)-2*temp)*arcs_cost_parameters(4,a&
     &rc)+(temp-arcs_cost_parameters(1,arc))*SQRT((temp-arcs_cost_parameters(1,arc))**2+arcs_cost_parameters(2,arc)**2)+&
      arcs_cost_parameters(2,arc)**2*(LOG(temp-arcs_cost_parameters(1,arc)+SQRT((temp-arcs_cost_parameters(1,arc))**2+arcs_cost_pa&
     &rameters(2,arc)**2))-LOG(arcs_cost_parameters(4,arc)-arcs_cost_parameters(1,arc))))
      END DO
      ELSE
      arcs_costs=0.0_r_wp
      END IF
      END IF
      
      
      CALL StopTimer(ff_elemental_costs_timer)
      
      
      END SUBROUTINE FFElementalCosts
      
      
      
      END MODULE FF_Cost_Functions