Calculating log for each array element

[LUK ShunTim]

DimitryASuplatov wrote:
> 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?

Most octave functions works on matrices.

octave:1> a=[1 2 3 4];
octave:2> log(a)
ans =

    0.00000   0.69315   1.09861   1.38629

> 2/ How to convert my array a to list?
> 3/ How to append to array?

Is this what you want?
octave:3> b=[a 10]
b =

     1    2    3    4   10

octave:4> c=[a b]
c =

     1    2    3    4    1    2    3    4   10

> 
> I really appreciate your help!
> Thank you!
> 
> SDA

The octave manual is online at
http://www.gnu.org/software/octave/doc/interpreter/

Regards,
ST
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