[R] vectorization help please

[Bill Simpson]

> > What is a smarter way of doing:
> > 
> > for(i in 1:xn)
> > for(j in 1:yn)
> > {
> > im2[i,j]<- im[i,j]* (-1)^(i+j)
> > }
> 
> 
>  im * (-1)^(row(im) + col(im))
> 
> Uwe
> 
Thanks very much Uwe.

Bill 

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