#install.packages("plotrix")  


  
x<-c(1,2,3,4,5,6,7,8,9,10)
x
y<-rep(c(1,2,3,4,5), each=2)
y
a<-data.frame(x,y)
a

exercicio.2<- function(x,y)
{
  if (length (x)==length (y)) 
  {
    x11()
    par(mfrow = c(3,2))
    library(plotrix)
    multhist(list(x,y))
    density.x<-density(x)
    density.y<-density(y)
    plot(NA, xlab="", ylab="", xlim=c(0,max(density.x$x, density.y$x)), 
         ylim=c(0,max(density.x$y, density.y$y)))
    lines(density.x, col="red")
    lines(density.y, col="blue")
        boxplot(x,y, xaxis="n", col=c("red", "blue"))
    axis(1, 1:2, c("x", "y"))
    plot(y~x)
    qqnorm(x, col="red", main="QQ Plot de x")
    qqnorm(y, col="blue", main="QQ Plot de y")
    par(mfrow=c(1,1))
    return (list(summary(x),summary(y), cor(x,y)))
  }
  else 
  {
    stop ("x e y devem ter o mesmo tamanho")
  }
}