its package: inexplicable date-shifting ?!

install.packages('its')
install.packages('Hmisc')
require(its)
m <- matrix(1:2, nrow=2)
m

its.format('%Y%m%d')

rownames(m) <- c('20040813', '20040814')
m

its(structure(m))

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Luis Torgo
Sent: Wednesday, April 27, 2005 7:42 AM
To: r-help at stat.math.ethz.ch
Subject: [R] Recursive calculation of a series of values

Dear R-users,

I'm felling kind of blocked on a quite simple problem and I wonder if 
someone could give me a help with it.

My problem:

x[0] = 100
x[1] = (1+v[1])*x[0]
x[2] = (1+v[2])*x[1]
...

i.e.

x[i] = (1+v[i])*x[i-1]
and x[0]=k

Given a set of v values I wanted to obtain the corresponding
x values in
an efficient way (i.e. without a for loop).

For instance, if x[0] = 100 and v = c(0.2,-0.1,0.05) then I would get
x = c(120,108,113.4)

I'm almost sure the function filter() from package tseries is the key 
for getting these values but I'm really blocked.

Any help is much appreciated.

Lu??s Torgo

--
Luis Torgo
 FEP/LIACC, University of Porto   Phone : (+351) 22 339 20 93
 Machine Learning Group           Fax   : (+351) 22 339 20 99
 R. de Ceuta, 118, 6o             email : ltorgo at liacc.up.pt
 4050-190 PORTO - PORTUGAL        WWW   : 
http://www.liacc.up.pt/~ltorgo