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taking the Log2 values


 
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# 1  
Old 08-04-2009
taking the Log2 values

Hi,

I am able to take the log value for the third column of a file using the script below. But I want to take the log2 (not the log). How would I write that?

thanks

awk 'BEGIN {OFS="\t"} {print $1, $2, log ($3)}'
# 2  
Old 08-04-2009
Post the input and the expected output.
# 3  
Old 08-04-2009
I don't know awk, but if you can take a log, you can take a base 2 log.

Given that you know X and you want to know log2 X:
Code:
log2 X = Y
2 ** (log2 X) = X = 2 ** Y
log X = Y log 2
Y = log X / log 2

Or roughly

log2 X = 3.322 log X


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