fRE_pitch Function

  FUNCTION fRE_pitch(g)
    REAL(rp), INTENT(IN) :: g ! Relativistic gamma factor
    REAL(rp) :: fRE_pitch
    REAL(rp) :: D
    REAL(rp) :: g0,g1,f0,f1,m
    INTEGER :: index

    index = MINLOC(ABS(h_params%g - g),1)
    D = h_params%g(index) - g

    if (D.GT.0) then
       f0 = h_params%fRE_pitch(index-1)
       g0 = h_params%g(index-1)

       f1 = h_params%fRE_pitch(index)
       g1 = h_params%g(index)
    else
       f0 = h_params%fRE_pitch(index)
       g0 = h_params%g(index)

       f1 = h_params%fRE_pitch(index+1)
       g1 = h_params%g(index+1)
    end if

    m = (f1-f0)/(g1-g0)

    fRE_pitch = f0 + m*(g - g0)
    fRE_pitch = 180.0_rp - fRE_pitch
  END FUNCTION fRE_pitch