| Re: help IDL with some equations implementation and optimized coding [message #71143] |
Tue, 01 June 2010 09:50 |
lila hadji
Messages: 7
Registered: June 2010
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Junior Member |
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On 1 juin, 14:56, Jeremy Bailin <astroco...@gmail.com> wrote:
> On Jun 1, 1:30 am, lila hadji <lhad...@gmail.com> wrote:
>
>
>
>> Dear everybody,
>
>> I tried to implement the dictionary update step in the Method of
>> Optimal Directions, as explained in the paper (basically equations 8,
>> 9, 17, 18 and 25)
>
>> % "Method of optimal directions for frame design",
>> % K. Engan, S. O. Aase, and J. H. Husøy,
>> % in Proc. ICASSP, Phoenix, AZ, Mar. 1999, pp. 2443Ð2446.
>
>> First link of the page:
>
>> http://scholar.google.com/scholar?hl=fr&q=%22Method+of+o ptimal+direct...
>
>> The problem is that I didn't obtain good results - as it is expected
>> within the paper - with my implementation and I was wondering of
>> anyone can check out the code and the equations in the paper and help
>> me out why my code does not give the expected results and if there is
>> any improvements I can do on the code to get rid of the for-loop,
>> please?
>
>> Here is the version with the loop.
>
>> ;;#IDL Code#
>> $Main$
>
>> ;N=16 : size of each sample
>> ;m=64: number of samples
>> ;k=32:number of atoms in the dictionary to be learned
>
>> ;Y=randomn(seed,m,n) : samples
>> ;D=randomn(seed, k,n): dictionary to be learned
>> ;X=randomn(seed,m,k): sparse codes to construct in the domain D
>
>> B=dblarr(N,k,/nozero)
>> ones=dblarr(N,/nozero)
>> ones(*)=1
>
>> A=invert(transpose(x)#X,/double)
>> R=Y-D##X
>
>> for i=0,k-1 do begin
>> xi=X(*,i)
>> B(*,i)=total((ones##xi)*R,1)
>> end
>
>> delta=A##B
>> D=D+transpose(delta)
>> end
>
>> ;; #IDL Code#
>
>> Thank you very much for your help in advance.
>> Cheers
>> Lila
>
> I don't know about the first question, but as for the second you can
> replace lots of that code including the for loop with:
>
> B = matrix_multiply(R, X, /atranspose)
>
> -Jeremy.
Thank you very much, it's actually the same. I didn't see the
matrices' multiplication in the first place. It actually works and is
loop-free besides the outer loop that is necessary for the
convergence.
Thank you very much for your help!
Cheers
Lila
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| Re: help IDL with some equations implementation and optimized coding [message #71149 is a reply to message #71143] |
Tue, 01 June 2010 05:56  |
Jeremy Bailin
Messages: 618
Registered: April 2008
|
Senior Member |
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On Jun 1, 1:30 am, lila hadji <lhad...@gmail.com> wrote:
> Dear everybody,
>
> I tried to implement the dictionary update step in the Method of
> Optimal Directions, as explained in the paper (basically equations 8,
> 9, 17, 18 and 25)
>
> % "Method of optimal directions for frame design",
> % K. Engan, S. O. Aase, and J. H. Husøy,
> % in Proc. ICASSP, Phoenix, AZ, Mar. 1999, pp. 2443Ð2446.
>
> First link of the page:
>
> http://scholar.google.com/scholar?hl=fr&q=%22Method+of+o ptimal+direct...
>
> The problem is that I didn't obtain good results - as it is expected
> within the paper - with my implementation and I was wondering of
> anyone can check out the code and the equations in the paper and help
> me out why my code does not give the expected results and if there is
> any improvements I can do on the code to get rid of the for-loop,
> please?
>
> Here is the version with the loop.
>
> ;;#IDL Code#
> $Main$
>
> ;N=16 : size of each sample
> ;m=64: number of samples
> ;k=32:number of atoms in the dictionary to be learned
>
> ;Y=randomn(seed,m,n) : samples
> ;D=randomn(seed, k,n): dictionary to be learned
> ;X=randomn(seed,m,k): sparse codes to construct in the domain D
>
> B=dblarr(N,k,/nozero)
> ones=dblarr(N,/nozero)
> ones(*)=1
>
> A=invert(transpose(x)#X,/double)
> R=Y-D##X
>
> for i=0,k-1 do begin
> xi=X(*,i)
> B(*,i)=total((ones##xi)*R,1)
> end
>
> delta=A##B
> D=D+transpose(delta)
> end
>
> ;; #IDL Code#
>
> Thank you very much for your help in advance.
> Cheers
> Lila
I don't know about the first question, but as for the second you can
replace lots of that code including the for loop with:
B = matrix_multiply(R, X, /atranspose)
-Jeremy.
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