t.test_multiple <- function(x, y, m0=0, alternative = "two.sided") {
  M1 <- mean(x)
  M2 <- mean(y)
  n1 <- length(x)
  n2 <- length(y)
  S <- sqrt((var(x) / n1) + (var(y) / n2))
  statistic <- (M1 - M2 - m0) / S
  
  p <- if (alternative == "two.sided") {
    2 * pt(q=abs(statistic), df=n1+n2-2, lower.tail=FALSE)
  } else if (alternative == "less") {
    pt(q=statistic, df=n1+n2-2, lower.tail = TRUE)
  } else {
    pt(q=statistic, df=n1+n2-2, lower.tail = FALSE)
  }

  value <- list(mean1 = M1, mean2 = M2, df=n1+n2-2, m0 = m0, statistic = statistic, p.value = p, alternative = alternative)
  
  return(value)
}


# niezależne
load("Bledy.RData")
attach(Bledy)

t.test(x=Blad, y=Kod,var.equal=T,alternative='less')

t.test_multiple(x=Blad, y=Kod, alternative='less')