library(nnet)

x<-sort(runif(300,0,2))
y<-0.2*x^5 - x^3 + 0.03*x^7 + 0.5*rnorm(300)
plot(x,y,col="red")
lines(x, 0.2*x^5-x^3+0.03*x^7,col="blue")

d<-data.frame(x,y)
names(d)<-c("X","Y")
n<-nnet(Y~X,size=10,linout=T,data=d,maxint=40)
pn<-predict(n,d)
summary(n)
lines(x,pn[,1],type="l",lw=2)


x<-sort(runif(300,0,2))
y<-0.2*x^5 - x^3 + 0.03*x^7 + 0.5*rnorm(300)
plot(x,y,col="red")
lines(x, 0.2*x^5-x^3+0.03*x^7,col="blue")

n<-nnet(Y~X,size=20,linout=T,data=d,maxint=40)

pn<-predict(n,d)

var(x-pn[,1])
lines(x,pn[,1],type="l",lw=1)



####efecto punto de arranque
for (i in 1:20)
{n<-nnet(Y~X,size=30,linout=T,data=d)
pn<-predict(n,d)
lines(x,pn[,1],type="l",lw=1)
}