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Subject: Re: quick search of a binary array within a binary matrix.
Date: Tue, 31 May 2011 01:40:05 +0000 (UTC)
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"Roger Stafford" wrote in message <is168a$fk2$1@newscl01ah.mathworks.com>...
> ..........
>   One thing is certain.  The code
> 
> tmp=find(b*B'==sum(b));
> 
> will not get the answer you seem to be asking for by an conceivable stretch of the imagination.
> 
> Roger Stafford
- - - - - - - - -
  It has occurred to me that by "b is contained in B" you might have meant that at least one of the rows of B (after being converted to a matrix) has the property that each of its binary bits is a 1 wherever the corresponding b vector has a 1 - that is, that a 1 denotes membership in the set of possible columns indices - rather than that the two rows are bit-for-bit equal.  If the former was your meaning of 'contained in', then the matrix multiplication you mentioned would indeed work properly.

  My comment about that is twofold.  I think you should have used a better way of wording your problem than just "contained in", and I needed a greater "stretch of the imagination".

Roger Stafford