[R] Recursive algorithm

David Winsemius dwinsemius at comcast.net
Mon Nov 1 13:18:21 CET 2010

On Nov 1, 2010, at 6:12 AM, Megh Dal wrote:

> Dear friend, I have to construct some recursive algorithm for which  
> I used some for loop like:
> res <- vector(length=10000)
> res[1] = 0
> for (i in 2:(10000+1)) res[i] <- res[i-1]*........some function

res[2:(10000+1)] <- res[1:10000]*mysteryfunction(2:(10000+1))    #  
might work if you created res as length 10001.

  In the current situation you should have been getting an error that  
you are not telling us about when you got to the end and tried to  
assign to res[10001]. Anyway, it's more likely the case that the  
mystery function is eating up time rather than the loop.

> I have noticed that this is taking too much time. Is there any way  
> to speed up things?

David Winsemius, MD
West Hartford, CT

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