[CppAD] Re: vector<bool>

[Brad Bell]

Thanks for the comments about why a packed version of boolean vectors 
should not have been made a specialization of std::vector.

SimpleVectors, as defined by
    http://www.coin-or.org/CppAD/Doc/simplevector.htm
are not necessarily containers, on the other hand it is possible that 
some day CppAD::vector
    http://www.coin-or.org/CppAD/Doc/cppad_vector.htm
may be extended to be both a simple vector and a container. As per Bobs 
comments in
    http://list.coin-or.org/pipermail/cppad/2005-October/000003.html
this would not be possible if CppAD::vector<bool> uses packed memory 
allocation.

Another drawback to packing booleans is speed considerations.
Thus a separate class was created for this purpose,  see the heading 
vectorBool in
    http://www.coin-or.org/CppAD/Doc/cppad_vector.htm
   
P.S.
Packed boolean vectors were added to CppAD in preparation for computing 
sparsity structure for Jacobians and Hessians.