Calculating log for each array element

[DimitryASuplatov]

Hello,

I have array with some values initialized as

a = load <filename>

I want now to create another array b so as b[i] = log(a[i])
I do this as follows

for i = 1:length(a)
	b(i) = log(a(i))
endfor

This works but it takes to long

1/ Is there any way to speed this up?
2/ How to convert my array a to list?
3/ How to append to array?

I really appreciate your help!
Thank you!

SDA