Re: Multicomponent arrays in Blitz++

From: Todd Veldhuizen (tveldhui@oonumerics.org)
Date: Fri Jun 19 1998 - 14:58:30 EST


Matthew Weippert wrote:

> Have you checked blitz++ with egcs-1.0.3?

1.0.3 is no good. See
http://oonumerics.org/blitz/contribute/blitz-dev/archive/0031.html

You need a recent snapshot (egcs-19980615) to compile blitz. Once
egcs 1.1 comes out, all should be bliss.

> I am a bit confused about multicomponent arrays verses higher
> dimensional arrays. For example, a multispectral image could be
> represented by a three dimensional array _or_ a two dimensional
> multicomponent array. (Right?) What are the differences, trade-offs
> etc?

I would say that a multicomponent array is more powerful. At
some point I'll provide a "flatten" function which will turn
(for example) Array<RGB24,2> into Array<char,3>. It's much
harder to go in the reverse direction. Also, if you have
objects such as RGB24, HSV24, etc. then you can do this:

Array<RGB24,2> A(128,128);
Array<HSV24,2> B(128,128);

B = A;

And it will convert from RGB24 to HSV24, provided HSV24 has appropriate
conversion methods defined. Doing this with a 3-dimensional array is
much clumsier.

Cheers,
Todd



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