subroutine ip2ij (ip,imx,i,j)
c
c=======================================================================
c                                                                    ===
c  This routine decodes an index of the type:                        ===
c                                                                    ===
c     ip = i + (j-1)*imx                                             ===
c                                                                    ===
c=======================================================================
c
c-----------------------------------------------------------------------
c  Define local data
c-----------------------------------------------------------------------
c
      integer i,imx,ip,j
c
c=======================================================================
c  Begin executable code
c=======================================================================
c
      i = mod(ip,imx)
c
      if (i.eq.0) i = imx
c
      j = (ip-i)/imx + 1
c
      return
      end