[R] Bug or failing understanding?

[ripley@stats.ox.ac.uk]

On Wed, 26 Jun 2002, kjetil halvorsen wrote:

> Hola!
>
> I seem to remember i used to have the same name of argument and default
> value in argument list to functions, but (rw1.5.1) this seems not to
> work:
>
> > x <- 3
> > test <- function(x=x) x*x
> > test(7)
> [1] 49
> > test()
> Error in test() : recursive default argument reference
>
>
> here is a code fragment from lm() using the same syntax:
>
>
>  else {
>         x <- model.matrix(mt, mf, contrasts)
>         z <- if (is.null(w))
>             lm.fit(x, y, offset = offset, ...)
>         else lm.wfit(x, y, w, offset = offset, ...)
>
> What is wrong?

You example is a call, and your usage is a formal argument. Yours sets the
default for `x' to x, which does not exist.  lm's calls lm.fit with named
argument `offset'.

>
> Kjetil Halvorsen
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-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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