         y=sapply(1:nrow(x), function(i) sapply(1:ncol(x), function(j)
getrc(i, j)))



Arvin Zolfaghari, Ph.D.



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From: Arvin Zolfaghari
Sent: 08 November 2010 14:35
To: 'Markus.Gesmann@lloyds.com'
Subject: question



Hi List,

I am trying to apply a
function to all elements of a matrix. I can use two consequent ' for'
loops, but it is really slow process. I can also use the sapply as follows,
but it is 10% faster, is there any other faster way (like fft)?

I got a matrix of x=matrix(0,1000,2000)

I want to load it with myfunction

first option:
For ( i in nrow(x)){

  For(j in nrow(x)){

    x=myfunction(i,j)

}}

second option:
t(sapply(1:nrow(x), function(i) sapply(1:ncol(x), function(j)
getrc(i, j))))

both option 1 and 2 work, but so slow. I appreciate your help.
thanks
Alireza

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