[eigen] Using custom scalar types

[Brad Bell <bradbell@xxxxxxxxxx>]

Looking at the example in
    
http://eigen.tuxfamily.org/dox/TopicCustomizingEigen.html#CustomScalarType
one sees
    ... snip ...
    IsInteger = 0,
    IsSigned,
    ReadCost = 1,
I suspect that IsSigned should be 1 for this example ?

Furthermore, one also sees
    ... snip ...
    inline adouble internal::sin(const adouble& x) { return sin(x); }
inline adouble internal::cos(const adouble& x) { return cos(x); }
inline adouble internal::pow(const adouble& x, adouble y) { return 
pow(x, y); }
    ... snip ...
Is this a typo, or should the argument y be passed by value instead of 
by const reference ?