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Re: Differentiation in IDL [message #50643]

Mon, 16 October 2006 07:31

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Allan Whiteford writes:

> Surely when you type:
>
> dx = DERIV(x * !dtor,data)
>
> you're actually doing:
>
> d/d(x*!dtor) (sin(x*!dtor))
>
> which is:
>
> cos(x*!dtor)
>
> i.e. you shouldn't need to divide the result by !dtor.
>
> Of course, declaring x as findgen(360)*!dtor to start with looks a lot
> cleaner and is probably easier to follow, but I don't think what was
> suggested by Wox gives the wrong answer.

I think Bradley was suggesting an alternative way
of getting to the same answer. And, indeed it does.
His explanation adds insight to the original problem.

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: Differentiation in IDL By: David Fanning on Mon, 16 October 2006 07:31
		Re: Differentiation in IDL By: Allan Whiteford on Mon, 16 October 2006 07:26
		Re: Differentiation in IDL By: Braedley on Mon, 16 October 2006 07:15
		Re: Differentiation in IDL By: David Fanning on Mon, 16 October 2006 06:59
		Re: Differentiation in IDL By: David Fanning on Mon, 16 October 2006 06:56
		Re: Differentiation in IDL By: Wox on Mon, 16 October 2006 06:54

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