max does not support sparse boolean matrix

[pbellec]

Thanks for the quick answer David. I will try to apply the patch and
recompile next week. I am not sure I correctly understands what the patch
does though

David Bateman-2 wrote:
> 
> Something like the attached should make the behavior the same as the full
> types
> 

If it is converting the max to a full array, that would not do. if max is
just a scalar it would have no impact, but commands like max(a,[],1) can
generate big vectors or arrays. It would be important to keep the sparse
attribute, and also the boolean type for cases where memory load is a
critical issue. 


David Bateman-2 wrote:
> 
> (what does matlab do in this case?).
> 

Matlab 7.4.0.336 (R2007a) is actually messing up the types. It keeps the
array sparse, but goes from boolean to double :

>> a = sparse([true false; false false]);
>> whos a
  Name      Size            Bytes  Class      Attributes

  a         2x2                17  logical    sparse    
>> max_a = max(a,[],1)

max_a =

   (1,1)        1
>> whos max_a
  Name       Size            Bytes  Class     Attributes

  max_a      1x2                36  double    sparse    

I hope this helps,

Pierre


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