problem to use figure fonction

Hi,

I'm trying to change a figure I just plot, the size or the face color etc...
I used the figure fonction in ipython:

a = arange(10)
plot(a)
figure(num=1, figsize=(10,10),facecolor='w')

but that change nothing on the figure 1.

I read the doc and I see:

figure : create or change active figure

so there are something I miss or misundertand so could explain me where is my error.

Thanks,

Nicolas