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Re: Derivative [message #60986 is a reply to message #55080]

Tue, 01 July 2008 12:11

wxf
Messages: 6
Registered: March 2007

Junior Member

On Jul 2, 3:05 am, Vince Hradil <hrad...@yahoo.com> wrote:
> On Jul 1, 1:58 pm, w...@bao.ac.cn wrote:
>
>> I have a 2-D array (a image) A. I want to know its partial
>> derivatives along X direction and Y direction.
>> dA(x,y)/dx=B
>> dA(x,y)/dy=C
>> B and C should also be 2-D array.
>> I want to know if IDL has some function or operator can do this job
>> directly.
>> If it has not those I wanted, then I must write some program according
>> to "Spline and Lagrange".
>> I am not a foolish boy. But I am a lazy boy.
>> Who can tell me if IDL can do this job for me?
>> Thanks!
>
> have you tried deriv()? Have you tried:
> IDL> ?

yes,I have used deriv() before.But it only works for one dimension.
If I use it to differentiate a 2-D image along one direction, then I
must use "for i= , do begin .....endfor". That is too slow.
Could you give me more hints?

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[Message index]

		Derivative along one dimension of a data cube? By: Ryan[1] on Sat, 28 July 2007 09:30
		Re: Derivative By: Vince Hradil on Tue, 01 July 2008 12:36
		Re: Derivative By: wxf on Tue, 01 July 2008 12:11
		Re: Derivative By: Vince Hradil on Tue, 01 July 2008 12:05

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