Calculating sum of squares from density estimates

Rainer M Krug <r.m.krug at gmail.com> wrote in
news:4798991D.3000607 at gmail.com: 

Hi

I have some density estimates obtained from density(). I would like
to calculate the sum of squares of these. As the x values of the
estimates are not the same, and I would prefer not to restrict the
estiomate to a certain range of x values, how can I do the
calculation? 

Lets say:

d1 <- density(Data1)
d2 <- density(Data2)

If the x values would be the same, I would:

ssq <- sum( (d1$y - d2$y)^2 )

but as it isn't, I can't do that.

is there an easy way to get the sum of squares?

Presumably there is a common domain for these densities. Consider 
forcing the x values to be the same by identically specifying n=, 
from=, and to=?

?density
x <- rnorm(200,1,1)
x2 <- rnorm(200,1,1)
d1 <- density(x, n=512, from=-1, to= 4)
d2 <- density(x2, n=512, from=-1, to= 4)
ssq <- sum( (d1$y - d2$y)^2 )
ssq

[1] 0.4722924

x <- rnorm(200,1,1)
x2 <- rnorm(200,1.5,1)
d1 <- density(x, n=512, from=-1, to= 4)
d2 <- density(x2, n=512, from=-1, to= 4)
ssq <- sum( (d1$y - d2$y)^2 )
ssq

[1] 2.111498