set.seed(100)

## Known parameters
lambda <- 2
N = 1000


## STraight from R

a1 = mean(val1<- rexp(N,lambda))


## Now using the CDF trick 

randomEXP <- function(N, lambda)
{
val2 <- NULL
for (i in 1:N) {
r[i] <- runif(1,0,1)
x[i] <- (-1/lambda)*log(1-r[i])
val2 <- c(val2, x[i]) 
}
print(val2)
}

a2 = mean(randomEXP(1000,2))


## Finding difference between the two techniques.. 
diff = a1 - a2

print(diff)