On 7/3/2013 2:13 PM, Doug York wrote:
> ....
>
> Now
> (%i7) tellsimpafter(cos(aa)-sqrt(3)*sin(aa),-2*cos(aa-'gam))$
> tellsimpafter(sqrt(3)*sin(aa)-cos(aa), 2*cos(aa-'gam))$
>
>
Both rules are really bad ideas. You are advising "+" that if it sees
EXACTLY 2 arguments, and they are EXACTLY what you specify,
that the rhs should be returned. So something like cos(x)-sqrt(3)*sin(x)+1
WILL NOT MATCH.
It is much better to use tellsimp( ...) only on functions of your own,
f,g,etc or
non-commutative functions of a fixed number of arguments. e.g. sin().
Not ..+...+.....
You could, if you wish, replace sin(aa) by(
2*cos(aa-'gam)-cos(aa))/sqrt(3).
or perhaps use ratsubst to find, for each argument of cos, say p, all
occurrence that can be divided out, of sqrt(3)*sin(p)-cos(p).
RJF