powell <- function(g)
{
	x1 <- g[1]
	x2 <- g[2]
	x3 <- g[3]
	x4 <- g[4]
	(x1 + 10 * x2)^2 + 5 * (x3 - x4)^2 + (x2 - 2 * x3)^4 + 10 * (x1 - x4)^4
	
}
powell.p <- matrix(c(
3, -1,  0,  1,
0, -1,  0,  1,
3,  0,  0,  1,
3, -1,  1,  1,
3, -1,  0,  0
), nrow=5, ncol=4, byrow=T, dimnames=list(NULL, c(
"x1", "x2", "x3", "x4"
)))