Axes control

I'm trying to make a plot where instead of the y-axis being

    > oriented in the traditional sense (large numbers on top, small
    > on bottom) it needs to be oriented in the reverse sense (small
    > numbers on top, large on bottom).

    > Now, my first thought on how to do this was the following:

    >>>> plot(x,-y) pos,lab = yticks()
    >>>> yticks(pos,map(str,-array(pos)))

Just try setting

ylim(ymax, ymin)

instead of explicitly mucking with the ticks. Eg,