[R] outer

[Peter Dalgaard BSA]

Peter Holzer <holzer at stat.math.ethz.ch> writes:

> Hello Sean
> 
> When using outer you need vectorized functions. I think in your case it
> would be enough to change the last line of your function to
> 
> ifelse(r==0, y, gcd(y,r))

Nope. Since ifelse() evaluates both alternatives, you'll have an
unterminating recursion. The only sure-kill way is to do an explicit
vectorization:

gcd.v <- function(x,y) sapply(seq(along=x),function(i)gcd(x[i],y[i]))
outer(1:5,1:5, gcd.v)



-- 
   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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