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Re: Calculate gradient [message #70085 is a reply to message #70084]

Fri, 12 March 2010 14:37

pgrigis
Messages: 436
Registered: September 2007

Senior Member

Hi,

the simpler solution would be to use the "shift" function
to calculate the dx and dy component of the gradient (whose
norm is sqrt(dx^2+dy^2) - similarly to the one-dimensional
case when you can compute the numerical derivative of x
as (x-shift(x,-1))/dx.

However you should be careful doing that with non-smooth
datasets.

Ciao,
Paolo

On Mar 12, 4:41 pm, mslarkin <enhlw...@gmail.com> wrote:
> Hi IDL experts,
> I have a 2-D array (2708x4060), containing reflectance data. Is it
> possible to calculate the reflectance gradient (i.e. the rate of
> reflectance change over distance or array grid) throughout the array,
> and then draw lines of equal gradient (note that they’re NOT contour
> lines)?
> Thank you very much for your help!
> IDL beginner

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[Message index]

		Re: Calculate gradient By: James[2] on Sat, 13 March 2010 00:35
		Re: Calculate gradient By: R.G.Stockwell on Fri, 12 March 2010 14:40
		Re: Calculate gradient By: pgrigis on Fri, 12 March 2010 14:37

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