pointwise1<-
function(results.predict, coverage = 0.95,a=recta)
{
	fit <- results.predict$fit
	limits <- qt(1 - (1 - coverage)/2, results.predict$df) * sqrt((results.predict$se.fit)^2+sum(residuals(a)^2)/a$df.residual)

	list(upper = fit + limits, fit = fit, lower = fit - limits)
}