[R] [R/S] question re solution

Peter Dalgaard p.dalgaard at biostat.ku.dk
Thu Sep 2 09:30:43 CEST 2004

Erin Hodgess <hodgess at gator.uhd.edu> writes:

> a <- 0.5*(outer(1:n3,1:n3,function(x,y,n2.=n2){n2. - pmax(x,y)}))
> Why doesn't this work please?

Because defaults are expressions to be evaluated in the function's
evaluation frame (i.e. the expression could depend on x and y for
instance). When you evaluate the function, it goes looking for n2 --
and you're back to square one, basically. You might use substitute to
poke a precomputed n2 into the function definition, but it isn't

   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

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