whitelist based doit()

[krastano...@gmail.com]

At the moment doit() permits blacklisting, meaning that it will *not*
operate on species mentioned in the hints. However I need doit() to
operate on only one single species (i.e. I want a whitelist based
doit). Is there a standard way to do this?

[Vinzent Steinberg]

I don't think so. It is the same problem as with expand():

In [12]: ((x+cos(2*x))**2).expand(trig=1)

Out[12]: 

 2          2                 4           2       

x  + 4*x*cos (x) - 2*x + 4*cos (x) - 4*cos (x) + 1

In [13]: ((x+cos(2*x))**2).expand(trig=1, multinomial=0)

Out[13]: 

                   2

/         2       \ 

\x + 2*cos (x) - 1/ 

Implementing it would be nice. (I honestly think that expand(trig=1) should only do trigonometric expansion, nothing else.) For expand() it is quite important that you don't expand everything possible, because it is very expensive.

Vinzent