
Re: MuPAD questions
Posted:
Dec 6, 1996 6:31 AM


zimmerma@leibniz.loria.fr (Paul Zimmermann) writes: >1.2.9a>> sysassign(D(r),0): # in previous versions, just write D(r):=0 #
Okay, this one worked great, thanks.
>Here again, you can directly define the value of diff(theta,t):
Hmm, this one didn't work so well. The cos(theta) example you gave worked, but what about this:
>>reset(); >>sysassign(diff(b,t),hold(diff)(b,t));sysassign(diff(c,t),hold(diff)(c,t));
diff(b, t) diff(c, t) >>a:=b*c; b c >>diff(a,t); 0 >>diff(b*c,t); 0
What's doing on there? I expected diff(b,t) * c + b * diff(c,t) via the product rule.
In fact, even this fails:
>>diff(5*b,t);
0
I'd expect 5*diff(b,t), but it seems like the sysassign is just doing an exact match instead of actually adding an evaluation rule.
Is there any way to do this?
Chris

