dynamic plotting of charts

[asad.naqvi]

hi,
i have designed a site in which i need to plot a dynamic line chart from the data that is received by the server. i have successfully designed the site and used jfree charts for plotting the graphs but i need the graph to be in x,-y co-ordinates instead of the usual x,y co-ordinates i.e the origin is on top with the y axis pointing downwards. can anyone help me out as to how to proceed with it since i think jfree charts does not have a predefined chart in the same format. thank u