C
C  User subroutine for defining distributed electromagnetic potential

      subroutine udempotential(vecPot,coords,nBlock,
     $     i_array,niarray,r_array,nrarray,c_array,ncarray)
c
      include 'aba_param.inc'
c
      dimension vecPot(nBlock,*),i_array(*),r_array(*)
      dimension coords(nBlock,*)
      character*80 c_array(*)
c
      parameter(i_udempot_kstep  = 1,
     $          i_udempot_kinc   = 2,
     $          i_udempot_noel   = 3,
     $          i_udempot_pottyp = 4,
     $          i_udempot_phase  = 5,
     $          i_udempot_proc   = 6)
c
      parameter(ir_udempot_time_1   = 1,
     $          ir_udempot_time_2   = 2)
c
      parameter(ic_udempot_surf = 1)
c
      parameter(i_pottyp_mvp = 1,
     $          i_pottyp_esp = 2)
c
      parameter(i_proc_lf_th = 1)
c
      parameter(i_udempot_phase_real = 1,
     $          i_udempot_phase_imag = 2)
      parameter (zero    = 0.d0,
     $           zp15     = 0.15d0,
     $           ten     = 10.d0)
c

       vecPot(1,1)=zero
       vecPot(1,2)=zero
       vecPot(1,3)=zero
c
      r = sqrt(coords(1,1)**2 + coords(1,2)**2 + coords(1,3)**2)
      rho = sqrt(coords(1,1)**2 + coords(1,2)**2)
      theta = atan2(rho, coords(1,3))
	  
      if (i_array(i_udempot_phase).eq.i_udempot_phase_real) then
       vecPot(1,1)=zero
       vecPot(1,2)=zp15*sin(theta)
       vecPot(1,3)=zero
      else if (i_array(i_udempot_phase).eq.i_udempot_phase_imag) then
       vecPot(1,1)=zero
       vecPot(1,2)=zero
       vecPot(1,3)=zero
      end if     
c
      return
      end