                             z = d3.format(".2f")(Math.abs(d.lod))
                             px = formatAxis(posByChr[d.chrx])(d.posx)
                             py = formatAxis(posByChr[d.chry])(d.posy)
-                            "(#{d.chrx}@#{px},#{d.chry}@#{py}) &rarr; z")
+                            "(#{d.chrx}@#{px},#{d.chry}@#{py}) &rarr; #{z}")
                     .direction('e')
                     .offset([0,10])
         svg.call(celltip)

        xmid_scaled = {}
        ymid_scaled = {}
        for chr in data.chrname
            xmid_scaled[chr] = calc_midpoints(pad_vector(xscale[chr](x) for x in posByChr[chr], (chrGap-2)/2))
            ymid_scaled[chr] = calc_midpoints(pad_vector(yscale[chr](y) for y in posByChr[chr], (chrGap-2)/2))

        # z-axis (color) limits; if not provided, make symmetric about 0
        zmin = matrixMin(data.lod)

                 .attr("stroke", "none")
                 .attr("stroke-width", "1")
                 .on("mouseover.paneltip", (d) ->
                                               d3.select(this).attr("stroke", "black").moveToFront()
                                               celltip.show(d))
                 .on("mouseout.paneltip", () ->
                                               d3.select(this).attr("stroke", "none").moveToBack()
                                               celltip.hide())

    # functions to grab stuff
