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Re: Gradient of two dimensional field [message #8298 is a reply to message #8200]

Wed, 19 February 1997 00:00

brian.jackel
Messages: 23
Registered: May 1996

Junior Member

In article <330B44DD.647C@cdc.noaa.gov> Andy Loughe <afl@cdc.noaa.gov> writes:
> Wilpert_Martin wrote:

>> we want to determine the electrical field from a given potential,
>> i.e. we have to calculate the gradient of a two dimensional array.
>>
>> Has anybody a idl-pvwave procedure to do this task?

> I would think that the shift function (used twice)
> could be used to do this.

Or even just

dx= a(1:*,*) - a
dy= a(*,1:*) - a

or

dx= a(1:n-1,*) - a(0:n-2,*)
dy= a(*,1:m-1) - a(*,0:m-2)

if "a" has dimensions of (n,m). When doing it the first way IDL takes
care of the different array sizes, with no perceptible performance hit.
The second way is perhaps a bit easier to read. Is this what you (the
original poster) were after?

Brian Jackel

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[Message index]

		Gradient of two dimensional field By: Wilpert_Martin on Wed, 19 February 1997 00:00
		Re: Gradient of two dimensional field By: Andy Loughe on Wed, 19 February 1997 00:00
		Re: Gradient of two dimensional field By: davidf on Wed, 19 February 1997 00:00
		Re: Gradient of two dimensional field By: stockwell on Wed, 19 February 1997 00:00
		Re: Gradient of two dimensional field By: Andy Loughe on Wed, 19 February 1997 00:00
		Re: Gradient of two dimensional field By: bowman on Wed, 19 February 1997 00:00
		Re: Gradient of two dimensional field By: brian.jackel on Wed, 19 February 1997 00:00
		Re: Gradient of two dimensional field By: Mirko Vukovic on Wed, 19 February 1997 00:00
		Re: Gradient of two dimensional field By: Andy Loughe on Mon, 03 March 1997 00:00

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