Environmental oddity.

I have two functions which appear to differ only in their environments.
They look like:

d1
function (x, mean = 0, sd = 1, log = FALSE) 
(((x - mean)/sd)^2 - 1) * if (log) 1 else dnorm(x, mean, sd)/sd
<environment: namespace:stats>

and

d2
function (x, mean = 0, sd = 1, log = FALSE) 
(((x - mean)/sd)^2 - 1) * if (log) 1 else dnorm(x, mean, sd)/sd

Typing "environment(d1)" gives

<environment: namespace:stats>

and typing "environment(d2)" gives

<environment: R_GlobalEnv>

The d2() function however gives an incorrect result:

d1(1,0,3,TRUE)
[1] -0.2962963
d2(1,0,3,TRUE)
[1] -0.8888889

In d2() the result of the if() statement does not get divided
by the final "sd" whereas in d1() it does (which is the desired/correct
result).

Of course the code is ridiculously kludgy (it was produced by "symbolic
differentiation").  That's not the point.  I'm just curious (idly?) as
to *why* the association of the namespace:stats environment with d1()
causes it to "do the right thing".

Can anyone give me any insight?  Ta.

cheers,

Rolf Turner

Honorary Research Fellow
Department of Statistics
University of Auckland
Phone: +64-9-373-7599 ext. 88276