I'm looking to run this for loop, but it takes an unacceptably long time (~20s) to execute. x and y are predefined vectors of length 2000000. 

```
for(i in 1:2000000)
{
    a <- runif(1)
    b <- runif(1)
    sqrtf <- sqrt(-log(b,10))

    x[i] <- sqrtf*cos(a)
    y[i] <- sqrtf*cos(b)
}

```

Any tricks available to speed this up a bit?

EDIT: fixed the sqrtf