Applying a function to each element of an array
If A is the matrix the answer is 2*(1 - 2^(-A)), which took about 10secs for an example of your size.
From \sum_{i=1}^n x^{1-i} = (1-x^{-n})/(1-x), E & OE.
On Fri, 7 Oct 2005, Tim Smith wrote:
I have a 7000x7000 matrix, and each element is an integer. For each
element, I want to apply the function :
wt <- 0
for(q in 1:count){
wt <- wt + 0.5^(q-1)
}
I get the value of 'count' from the elements in the matrix , and want to
store the corresponding 'wt' value for that element.
I suppose I could loop through the matrix, and apply the function to
each element but this would take a really really long time. Are there
any quicker ways to get the same result?
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) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595