Here is the Splus code I used to create a power contour plot that
emulates the code used in SAS.  Note how the (x,y) coordinates have
to be expanded (to emulate looping) and then listed as grid values when
contour plotting.  The power function has to be packed into a matrix
for the contour command--ordering of the coordinates is critical here--
you'll be able to tell if you got it right when you see the contour
plot.

s02_rep(seq(1,5),rep(15,5))
n_rep(seq(2,16),5)
ncvec_n*s02
a_5
nma_n*a-a
power_1-pf(qf(.95,a-1,nma),a-1,nma,ncvec)
contour(seq(2,16),seq(1,5),matrix(power,ncol=5),xlab="Sample Size",
 ylab="Effect")