[PATCH] Add gradient operator

[Jeffrey D. Oldham]

Richard Guenther wrote:

> Like Div, this adds DiffOps/Grad.  Needed for PIC2d to work.
>
> Ok?
>
> Richard.
>
>
> 2004Jul15  Richard Guenther <richard.guenther at uni-tuebingen.de>
>
>     * src/Field/DiffOps/Grad.h: new.
>     src/Field/DiffOps/Grad.UR.h: likewise.
>
>  
>
Yes, I like this patch.  I also like the vertical alignment of 
operator()s' long operands.

-- 
Jeffrey D. Oldham
oldham at codesourcery.com