[R] make a triple summation more efficient

kathie kathryn.lord2000 at gmail.com
Sat Nov 15 17:39:48 CET 2008


Dear R users... 


I made the R-code for this triple summation computation 

http://www.nabble.com/file/p20517134/a.jpg 

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Here is my code..


x=seq(.1,1,.1); l=10
y=seq(1,10); m=10
z=seq(.1,1,.1); n=10

sum(sapply(1:l, function(i) {sum(sapply(1:m, function(j) {sum(sapply(1:n,
function(k){exp(x[i]*y[j]*z[k]  )/gamma(y[j]+1)}))^(1.5)  }))}))

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In fact, this is a part of optimization. I guess if it is vectorized, then
the running time could be shortened.

How could I vectorize this? or any suggestion will be greatly appreciated.

Kathryn Lord
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