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Re: SparseArray, DensityGraphics, ContourGraphics, and SurfaceGraphics

• To: mathgroup at smc.vnet.net
• Subject: [mg54706] Re: SparseArray, DensityGraphics, ContourGraphics, and SurfaceGraphics
• From: Jon Harrop <usenet at jdh30.plus.com>
• Date: Sun, 27 Feb 2005 01:29:54 -0500 (EST)
• References: <cvc84d$qrb$1@smc.vnet.net> <cvk485$dat$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Jens-Peer Kuska wrote:
> what has a sparse matrix to do with a density graphics ?

RLE.

> ArrayPlot[] is only used to visualize the sparse matrix, but
> all the memory saving of the sparse matrix are destroyed when you
> expand every entry in the matrix (not only the non zero values) to a
> 3D Polygon[] with 4 corners in Plot3D[] ...

Only if you tesselate uniformly. If you adaptively subdivide then you can
retain sparseness.

> It seems a good design decision not to support this nonsens ...

The OPs question is perfectly valid. The answer, I suspect, is simply that
WRI have not yet implemented it. Although not insurmountable, this is not a
trivial problem to solve properly.

-- 
Dr Jon D Harrop, Flying Frog Consultancy
http://ffconsultancy.com