envelope.normal<-function(form=form,k=k,alfa=alfa){
alfa1<-ceiling(k*alfa)
alfa2<-ceiling(k*(1-alfa))
glm1<-lm(formula=form)
X<-model.matrix(glm1)
n<-nrow(X)  
p<-ncol(X)
H<-X%*%solve(t(X)%*%X)%*%t(X)
h<-diag(H)
lmi<-lm.influence(glm1)
si<-lmi$sigma
rp<-residuals(glm1)
ts<-rp/(si*(1-h)^0.5)
ident<-diag(n)  
epsilon<-matrix(0,n,k)  
e<-matrix(0,n,k)  
e1<-numeric(n)  
e2<-numeric(n)  
for(i in 1:k){  
      epsilon[,i]<-rnorm(n,0,1)  
      e[,i]<-(ident-H)%*%epsilon[,i]  
      u<-diag(ident-H)  
      e[,i]<-e[,i]/(u^0.5) 
      e[,i]<-sort(e[,i])  
               }  
for(i in 1:n){  
          eo<-sort(e[i,])  
          e1[i]<-eo[alfa1]  
          e2[i]<-eo[alfa2]  
             }  
xb<-apply(e,1,mean)
faixa<-range(ts,e1,e2)
par(pty="s")
qqnorm(e1,axes=F,xlab="",ylab="",type="l",ylim=faixa,lty=2)
par(new=T)
qqnorm(e2,axes=F,xlab="",ylab="",type="l",ylim=faixa,lty=2)
par(new=T)
qqnorm(xb,axes=F,xlab="",ylab="",type="l",ylim=faixa,lty=1)
par(new=T)
qqnorm(ts,xlab="Quantis da N(0,1)",ylab="Residuo Studentizado",ylim=faixa)
}