## Podiplomski studij statistike, 2002/2003
## V. Batagelj: Informacijska tehnologija v analizi podatkov
## Risanje funkcij v R-ju
## 10.jan 03 / 05.jan 03
##
# ------------------------------------------------------------------
## Grid

# risanje funkcij
f4 <- function(x){x^4 - 14*x^3 + 60*x^2 - 70*x }
curve(f4,0,7)

# Rosenbrock Banana function
fun <- function(x,y){100 * (y - x * x)^2 + (1 - x)^2}
x <- seq(-5,5,0.1); y <- x
z <- outer(x,y,fun)
contour(x,y,z)
contour(x,y,log(z),nlevels=20)

x <- seq(-0.5,1.5,0.01); y <- x; z <- outer(x,y,fun)
contour(x,y,log(z),nlevels=20)
image(x,y,log(z))
persp(x,y,log(z),zlim=c(-10,10),theta=180,phi=45)
persp(x,y,log(z),zlim=c(-11,6),theta=180,phi=-10)


# ------------------------------------------------------------------
## Lattice

library(lattice)
x <- seq(0.9,1.1,0.0025); y <- x
g <- expand.grid(x=x,y=y)
g$z <- fun(g$x,g$y); g$z <- log(g$z)
which.min(g$z)
[1] 3281
g$z[3281] <- -20
levelplot(z~x*y,data=g,cuts=50,xlab="x",ylab="y",
  main="Rosenbrock Banana",colorkey=FALSE)
wireframe(z ~ x * y,data=g,drape=TRUE,colorkey=TRUE,shade=TRUE)

pdf(file="ban1.pdf")
wireframe(z ~ x * y,data=g,drape=TRUE,colorkey=TRUE,shade=TRUE)
dev.off(); pdf(file="ban2.pdf")
wireframe(z ~ x * y,data=g,drape=TRUE,colorkey=TRUE,shade=TRUE,
  screen=list(z=30,x=-60))
dev.off(); pdf(file="ban3.pdf")
wireframe(z ~ x * y,data=g,drape=TRUE,colorkey=TRUE,shade=TRUE,
  screen=list(z=25,x=-50),scales=list(draw=FALSE))
dev.off()

# ------------------------------------------------------------------