iPhone SDK chart Core-Plot: How to keep the X axis and Y axis keep on the bottom and right whatever i scale how much

I am now creating a chart by using Core-plot in iphone sdk.

But i want the X-axis and Y-axis always stay on the bottom and right whatever how much did i enlarge or scale.

you can se开发者_如何学Ce what happened in the following picture , thank you:

Just add this line

y.isFloatingAxis=YES;

x.isFloatingAxis=YES;

if still axis moving then set NO instead of YES