unexpected behaviour of 'curve' function
"Guazzetti Stefano" <Stefano.Guazzetti at ausl.re.it> writes:
Dear all, curve(x^3*(1-x)^7, from = 0, to = 1) works as expected but, omitting the "xlim" or the "to" and "from" arguments and calling "curve" more than once: par(mfrow = c(2,2)) for (i in 1:4) curve(x^3*(1-x)^7) gives an expected (al least to me) result. Note also that a "pu" object is returned by curve
pu
[1] -0.1802445 1.1802445 The behaviour is reproducible with both R 2.0.0 and R 2.0.1 I can see that a promise of evaluation of "pu" is made within curve but I cannot understand completely what happens.
I think the upshot is just that it is taking the "from" and "to" from
par("usr") from the previous plot and every time you do so, it expands
a little (about 4%). Notice that it does not happen if you do this:
par(mfrow = c(2,2), xaxs="i")
for (i in 1:4)
curve(x^3*(1-x)^7)
Having pu end up in the global environment looks like a bug in
delay() but I don't think it has any influence on this particular
effect.
O__ ---- Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907