Adding differentiation/integration rules

>>>>> "Boris" == Boris Veytsman <borisv@lk.net> writes:

    >> From: Raymond Toy <toy at rtp>
    >> Date: 25 Sep 2001 09:53:01 -0400
    >> 
    Boris> Like this:
    >> 
    Boris> tellsimp(cn1(0),1);
    Boris> tellsimp(sn1(0),0);
    >> 
    >> Thanks1  That works.  However, what if I want sn1(.5, .8) to give me
    >> some number?  I don't know how to do that.


    Boris> Easy. This will substitute sn1 by the original sn iff both arguments
    Boris> are numerical:

[solution snipped]

Very nice.  Your help is very much appreciated.

I now have a final question.  sn has these properties:

sn(u/2)^2 = (1-cn(u))/(1+dn(u))

sn(2*u) = 2*sn(u)*cn(u)*dn(u)/(1-m*sn(u)^4)

How do I get maxima to understand this?  However, I don't want this
applied all of the time, just like the corresponding trig functions.

Thanks!

Ray