Computes likelihood for normal model with positive mean.
nplike(x, mu, alpha, beta, theta, cond, sub, item, lag, sigma2)
~~Describe x here~~
~~Describe mu here~~
~~Describe alpha here~~
~~Describe beta here~~
~~Describe theta here~~
~~Describe cond here~~
~~Describe sub here~~
~~Describe item here~~
~~Describe lag here~~
~~Describe sigma2 here~~