[Scilab-users] Hilbert transform query

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[Scilab-users] Hilbert transform query

Hello

A quick query. How would one define the Hilbert transform of a grid
for X and Y directions; looking for two solutions Hx and Hy (for the
real values).

Thanks
Lester
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Serge Steer-3 Serge Steer-3
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Re: Hilbert transform query

Le 05/02/2016 10:56, Lester Anderson a écrit :
> Hello
>
> A quick query. How would one define the Hilbert transform of a grid
> for X and Y directions; looking for two solutions Hx and Hy (for the
> real values).
Can you explain more precisely what you expect?
  Do you want to apply Hilbert transform to each column and to each rows
or to perform a 2D Hilbert transform?
Serge
>
> Thanks
> Lester
> _______________________________________________
> users mailing list
> [hidden email]
> http://lists.scilab.org/mailman/listinfo/users
>

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Re: Hilbert transform query

Hi Serge,

I am working with grid data, so looking for the 2D Hilbert, the
results I think should appear similar to doing a directional
derivative, where X highlights features with N-S trends and E-W for Y.

Lester



On 5 February 2016 at 12:24, Serge Steer <[hidden email]> wrote:

> Le 05/02/2016 10:56, Lester Anderson a écrit :
>>
>> Hello
>>
>> A quick query. How would one define the Hilbert transform of a grid
>> for X and Y directions; looking for two solutions Hx and Hy (for the
>> real values).
>
> Can you explain more precisely what you expect?
>  Do you want to apply Hilbert transform to each column and to each rows or
> to perform a 2D Hilbert transform?
> Serge
>>
>>
>> Thanks
>> Lester
>> _______________________________________________
>> users mailing list
>> [hidden email]
>> http://lists.scilab.org/mailman/listinfo/users
>>
>
> _______________________________________________
> users mailing list
> [hidden email]
> http://lists.scilab.org/mailman/listinfo/users
_______________________________________________
users mailing list
[hidden email]
http://lists.scilab.org/mailman/listinfo/users
Tim Wescott Tim Wescott
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Re: Hilbert transform query

Any time you go from 1D to 2D you suddenly end up with more than one way
to do things, so I'm pretty sure that "how would one..." should really
be worded "how would YOU...", or perhaps "how would someone in this
field...".

It sounds like you want to keep things rectilinear, so it may be best to
just apply the transform column-by-column and row-by-row.  That SHOULD
work, and if you do it as matrix operations it should be pretty fast in
Scilab.

On Fri, 2016-02-05 at 12:52 +0000, Lester Anderson wrote:

> Hi Serge,
>
> I am working with grid data, so looking for the 2D Hilbert, the
> results I think should appear similar to doing a directional
> derivative, where X highlights features with N-S trends and E-W for Y.
>
> Lester
>
>
>
> On 5 February 2016 at 12:24, Serge Steer <[hidden email]> wrote:
> > Le 05/02/2016 10:56, Lester Anderson a écrit :
> >>
> >> Hello
> >>
> >> A quick query. How would one define the Hilbert transform of a grid
> >> for X and Y directions; looking for two solutions Hx and Hy (for the
> >> real values).
> >
> > Can you explain more precisely what you expect?
> >  Do you want to apply Hilbert transform to each column and to each rows or
> > to perform a 2D Hilbert transform?
> > Serge
> >>
> >>
> >> Thanks
> >> Lester
> >> _______________________________________________
> >> users mailing list
> >> [hidden email]
> >> http://lists.scilab.org/mailman/listinfo/users
> >>
> >
> > _______________________________________________
> > users mailing list
> > [hidden email]
> > http://lists.scilab.org/mailman/listinfo/users
> _______________________________________________
> users mailing list
> [hidden email]
> http://lists.scilab.org/mailman/listinfo/users

--

Tim Wescott
www.wescottdesign.com
Control & Communications systems, circuit & software design.
Phone: 503.631.7815
Cell:  503.349.8432


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arctica1963 arctica1963
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Re: Hilbert transform query

So what would the syntax be for doing a column run Hilbert, and row run Hilbert?

It does sound like the suggesting would do what I think it is meant to.

X = hilbert(data) // does compute pretty fast!

At the moment I have used the netCDF code to read in GMT (net CDF)
data, which is a 601 x 601 matrix (x,y). So in order to do the column
and row method is it necessary to transpose the matrix, e.g. x = x' ?

Thanks for any pointers

On 5 February 2016 at 19:02, Tim Wescott <[hidden email]> wrote:

> Any time you go from 1D to 2D you suddenly end up with more than one way
> to do things, so I'm pretty sure that "how would one..." should really
> be worded "how would YOU...", or perhaps "how would someone in this
> field...".
>
> It sounds like you want to keep things rectilinear, so it may be best to
> just apply the transform column-by-column and row-by-row.  That SHOULD
> work, and if you do it as matrix operations it should be pretty fast in
> Scilab.
>
> On Fri, 2016-02-05 at 12:52 +0000, Lester Anderson wrote:
>> Hi Serge,
>>
>> I am working with grid data, so looking for the 2D Hilbert, the
>> results I think should appear similar to doing a directional
>> derivative, where X highlights features with N-S trends and E-W for Y.
>>
>> Lester
>>
>>
>>
>> On 5 February 2016 at 12:24, Serge Steer <[hidden email]> wrote:
>> > Le 05/02/2016 10:56, Lester Anderson a écrit :
>> >>
>> >> Hello
>> >>
>> >> A quick query. How would one define the Hilbert transform of a grid
>> >> for X and Y directions; looking for two solutions Hx and Hy (for the
>> >> real values).
>> >
>> > Can you explain more precisely what you expect?
>> >  Do you want to apply Hilbert transform to each column and to each rows or
>> > to perform a 2D Hilbert transform?
>> > Serge
>> >>
>> >>
>> >> Thanks
>> >> Lester
>> >> _______________________________________________
>> >> users mailing list
>> >> [hidden email]
>> >> http://lists.scilab.org/mailman/listinfo/users
>> >>
>> >
>> > _______________________________________________
>> > users mailing list
>> > [hidden email]
>> > http://lists.scilab.org/mailman/listinfo/users
>> _______________________________________________
>> users mailing list
>> [hidden email]
>> http://lists.scilab.org/mailman/listinfo/users
>
> --
>
> Tim Wescott
> www.wescottdesign.com
> Control & Communications systems, circuit & software design.
> Phone: 503.631.7815
> Cell:  503.349.8432
>
>
> _______________________________________________
> users mailing list
> [hidden email]
> http://lists.scilab.org/mailman/listinfo/users
_______________________________________________
users mailing list
[hidden email]
http://lists.scilab.org/mailman/listinfo/users
Serge Steer-3 Serge Steer-3
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Re: Hilbert transform query

X = hilbert(data)  computes the hilbert transform of data(:) not a N dimensionnal Hilbert transform.
Please find attached a function which is intended to compute the N dimensionnal Hilbert transform obtained applying
the 1D hilbert transform to all columns then to all rows, ....

This function exploits the ability of fft to compute all fft along a given dimension with a single call.
Serge
 


Le 08/02/2016 17:51, Lester Anderson a écrit :

> So what would the syntax be for doing a column run Hilbert, and row run Hilbert?
>
> It does sound like the suggesting would do what I think it is meant to.
>
> X = hilbert(data) // does compute pretty fast!
>
> At the moment I have used the netCDF code to read in GMT (net CDF)
> data, which is a 601 x 601 matrix (x,y). So in order to do the column
> and row method is it necessary to transpose the matrix, e.g. x = x' ?
>
> Thanks for any pointers
>
> On 5 February 2016 at 19:02, Tim Wescott <[hidden email]> wrote:
>> Any time you go from 1D to 2D you suddenly end up with more than one way
>> to do things, so I'm pretty sure that "how would one..." should really
>> be worded "how would YOU...", or perhaps "how would someone in this
>> field...".
>>
>> It sounds like you want to keep things rectilinear, so it may be best to
>> just apply the transform column-by-column and row-by-row.  That SHOULD
>> work, and if you do it as matrix operations it should be pretty fast in
>> Scilab.
>>
>> On Fri, 2016-02-05 at 12:52 +0000, Lester Anderson wrote:
>>> Hi Serge,
>>>
>>> I am working with grid data, so looking for the 2D Hilbert, the
>>> results I think should appear similar to doing a directional
>>> derivative, where X highlights features with N-S trends and E-W for Y.
>>>
>>> Lester
>>>
>>>
>>>
>>> On 5 February 2016 at 12:24, Serge Steer <[hidden email]> wrote:
>>>> Le 05/02/2016 10:56, Lester Anderson a écrit :
>>>>> Hello
>>>>>
>>>>> A quick query. How would one define the Hilbert transform of a grid
>>>>> for X and Y directions; looking for two solutions Hx and Hy (for the
>>>>> real values).
>>>> Can you explain more precisely what you expect?
>>>>   Do you want to apply Hilbert transform to each column and to each rows or
>>>> to perform a 2D Hilbert transform?
>>>> Serge
>>>>>
>>>>> Thanks
>>>>> Lester
>>>>> _______________________________________________
>>>>> users mailing list
>>>>> [hidden email]
>>>>> http://lists.scilab.org/mailman/listinfo/users
>>>>>
>>>> _______________________________________________
>>>> users mailing list
>>>> [hidden email]
>>>> http://lists.scilab.org/mailman/listinfo/users
>>> _______________________________________________
>>> users mailing list
>>> [hidden email]
>>> http://lists.scilab.org/mailman/listinfo/users
>> --
>>
>> Tim Wescott
>> www.wescottdesign.com
>> Control & Communications systems, circuit & software design.
>> Phone: 503.631.7815
>> Cell:  503.349.8432
>>
>>
>> _______________________________________________
>> users mailing list
>> [hidden email]
>> http://lists.scilab.org/mailman/listinfo/users
> _______________________________________________
> users mailing list
> [hidden email]
> http://lists.scilab.org/mailman/listinfo/users

_______________________________________________
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