# Unicorn errata

This web page describes changes made to Unicorn, and therefore changing imlementation of various exercises in the book "Uncertainty Analysis with High Dimensional Dependence Modelling" by D. Kurowicka and R.M. Cooke.

1. The functionality of "prev" function has been split into two functions now: "prev" and "prev0".

1.a) Function "udf1 = prev0(x) + 1" initializes udf1 with the value of x and at every iteration adds 1 to its own previous value. Hence at iteration n = 1 udf1 = x, at iteration n = k udf1 equals to the value of udf1 for n = k-1 plus 1.

1.b) Function "udf2 = prev(udf1)" at iteration n = k takes the value of udf1 at iteration n = k-1. For n = 1 udf2 = 0.

CHANGES TO PROJECTS IN THE BOOK:

Project 3.2 Epistemic and aleatory uncertainty: polio incidence

New UDF's are:
r = prev0(ro)
b = prev0(bo)
tr = b*(1 + 0.05*sin(day/356)) + e
s = prev0((mo + r)/b)*(1 - tr*prev(i) - mo) + mo*no
i = prev0((b*no - (mo + r))*mo/(b*(mo + r)))*(tr*prev(s) - (r + mo) + 1)
day = prev0(0) + 1