trh@ukc.UUCP (06/19/85)
On computing some large expressions via Macsyma the following statements
dn : diff(n,t);
dn0 : ev(dn, t=0);
produce a `can't differentiate w.r.t a number 0 ' message.
Looking at n it contains some
expt( long boring expression, <-1>)
messages in it, dn then contains
d
- expt( long boring expression, -1)
dt
and hence the catastrophe.
I've tried all ( well it seems like it!) combinations of simp, expand, diff
and eval in ev but I can't get rid of the expt.
Please can somebody help.
Tim Hopkins,
Computing Laboratory,
University of Kent,
Canterbury CT2 7NF
Kent
U.K.
{ trh@ukc.UUCP
trh%ukc@ucl-cs.ARPA
na.hopkins@su-score.ARPA }