subroutine  recos_qR(q_i, q_ip1, q_ip2, 
     &                        r_i, r_ip1, r_ip2,
     &                        rqR_iph )

c------------------------------------------------------------
c Calculates the reconstructed variables
c from the RIGHT using a minmod slope limiter.
c Note that the input coordinates are the coordinates
c of the cell centres (x_(i), x_(i+1) and x_(i+2)), 
c the output is at the cell boundary x_(i+1/2).
c------------------------------------------------------------

         implicit      none

         character*8   cdnm
         parameter   ( cdnm = 'recos_qR' ) 

         logical       ltrace
         parameter   ( ltrace = .false. )

         real*8        q_i,  q_ip1,   q_ip2
         real*8        r_i,  r_ip1,   r_ip2

         real*8        rqR_iph

         real*8        s_iph,    s_ip3h   
         real*8        sigma_ip1

         real*8        minmod 
         
c============================================================
c============================================================

         if ( ltrace ) then
            write(0,*) cdnm,':    q_i=', q_i
            write(0,*) cdnm,':  q_ip1=', q_ip1
            write(0,*) cdnm,':  q_ip2=', q_ip2
            write(0,*) cdnm,':  '
            write(0,*) cdnm,':    r_i=', r_i
            write(0,*) cdnm,':  r_ip1=', r_ip1
            write(0,*) cdnm,':  r_ip2=', r_ip2
            write(0,*) cdnm,':  '
         endif
         s_iph  = (q_ip1 - q_i)   / (r_ip1 - r_i)
         s_ip3h = (q_ip2 - q_ip1) / (r_ip2 - r_ip1)
         sigma_ip1 = minmod(s_iph, s_ip3h) 
         rqR_iph   = q_ip1 + sigma_ip1 * 0.5d0 * (r_i - r_ip1)
         if ( ltrace ) then
            write(0,*) cdnm,':  rqR_iph=', rqR_iph
         endif
         return
         end