[Insight-developers] itkPoint from a math perspective

George Stetten george@stetten.com
Thu, 19 Jul 2001 17:52:31 -0400


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>
> Gradients of functions and Normals to surfaces
> are "Covariant" vectors.
>
> Differences between points are "Contravariant"
> vectors.
>

Dear Luis,

Is this what you mean?

Since gradients are "intensity per unit distance," changing units from feet to inches makes the
gradient get smaller (in numbers), while it makes distance get larger (in numbers).

George




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<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
>

> Gradients of functions and Normals to surfaces
> are "Covariant" vectors.
>
> Differences between points are "Contravariant"
> vectors.
>

Dear Luis,

Is this what you mean?

Since gradients are "intensity per unit distance," changing units from feet to inches makes the
gradient get smaller (in numbers), while it makes distance get larger (in numbers).

George
 
 
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