anchor.diff:  
             ! If the wall is the midplane wall, we can just treat it as a
             ! plane, so don't need to do any fancy calculations.
  -          if(p%icell%i2+1 == geo%midplane.and.p%v%z.ne.0) then
  +          if(p%icell%i2 + 1 == geo%midplane .and. p%v%z .ne. 0) then
   
                ! If the photon is on the wall, then we don't add any intersections
  -             if(p%on_wall_id%w2 /= +1) call insert_t(-p%r%z/p%v%z,2, +1, geo%ew2(p%icell%i2+1))
  +             if(p%on_wall_id%w2 /= +1) call insert_t(-p%r%z / p%v%z, 2, +1, geo%ew2(p%icell%i2 + 1))
   
             else
   
                ! Compute the full intersections. Find the coefficients of the quadratic equation
  -             pA=v2_xy-v2_z*geo%wtant2(p%icell%i2+1)
  -             pB=rv_xy-rv_z*geo%wtant2(p%icell%i2+1) ; pB = pB + pB
  -             pC=r2_xy-r2_z*geo%wtant2(p%icell%i2+1)
  +             pA=v2_xy - v2_z * geo%wtant2(p%icell%i2 + 1)
  +             pB=rv_xy - rv_z * geo%wtant2(p%icell%i2 + 1) ; pB = pB + pB
  +             pC=r2_xy - r2_z * geo%wtant2(p%icell%i2 + 1)
   
                if(abs(pA) .gt. 0._dp) then  ! Solve ax^2 + bx + c = 0
   
                   ! Compute the full quadratic solutions
  -                call quadratic(pA,pB,pC,t1,t2)
  +                call quadratic(pA, pB, pC, t1, t2)
   
                   ! Check if the solutions are on the right side of the
                   ! mid-plane. The equation of the cone (z^2 = x^2 + y^2) does
                   ! not differentiate between a positive and a negative value,
                   ! so we have to check against the angle that was originally
                   ! specified for the wall.
  -                z1=p%r%z+p%v%z*t1
  -                if(z1 > 0._dp .neqv. geo%wtant(p%icell%i2+1) > 0._dp) t1 = huge(1._dp)
  -                z2=p%r%z+p%v%z*t2
  -                if(z2 > 0._dp .neqv. geo%wtant(p%icell%i2+1) > 0._dp) t2 = huge(1._dp)
  +                z1=p%r%z + p%v%z * t1
  +                if(z1 > 0._dp .neqv. geo%wtant(p%icell%i2 + 1) > 0._dp) t1 = huge(1._dp)
  +                z2=p%r%z + p%v%z * t2
  +                if(z2 > 0._dp .neqv. geo%wtant(p%icell%i2 + 1) > 0._dp) t2 = huge(1._dp)
   
                   ! If we are on the wall, then we should discard the
                   ! intersection with the smallest absolute value as this will
  
positive.code: 
            ! If the wall is the midplane wall, we can just treat it as a
            ! plane, so don't need to do any fancy calculations.
            if(p%icell%i2 == geo%midplane.and.p%v%z.ne.0) then
  
               ! If the photon is on the wall, then we don't add any intersections
               if(p%on_wall_id%w2 /= -1) call insert_t(-p%r%z/p%v%z,2, -1, geo%ew2(p%icell%i1))
  
negative.code:           else
  
               ! Compute the full intersections. Find the coefficients of the quadratic equation
               pA = v2_xy - v2_z * geo%wtant2(p%icell%i2)
               pB = rv_xy - rv_z * geo%wtant2(p%icell%i2) ; pB = pB + pB
               pC = r2_xy - r2_z * geo%wtant2(p%icell%i2)
  
               if(abs(pA) .gt. 0._dp) then  ! Solve ax^2 + bx + c = 0
  
                  ! Compute the full quadratic solutions
                  call quadratic(pA, pB, pC, t1, t2)
  
                  ! Check if the solutions are on the right side of the
                  ! mid-plane. The equation of the cone (z^2 = x^2 + y^2) does
  