Hi
if you want handle diff(f(x),x) with function context,
you can use pdiff package by Barton Willis.(thank you Barton)
(C1) load("pdiff.lisp")$
(C2) diff(f(x),x);
(D2) f (x)
(1)
(C3) subst(x=1,%);
(D3) f (1)
(1)
(C4) use_pdiff:false;
(D4) FALSE
(C5) diff(f(x),x);
d
(D5) -- (f(x))
dx
(C6) subst(x=1,%);
Attempt to differentiate with respect to a number:
1
-- an error. Quitting. To debug this try DEBUGMODE(TRUE);)
(C7) use_pdiff:true$
(C8) g(x):=subst(u=x,diff(f(u),u))$
(C14) g(1.1);
(D14) f (1.1)
(1)
(C15) g(t);
(D15) f (t)
(1)
this is OK.
Gosei Furuya (go_furuya@infoseek.jp)
> Quick question.
>
> How do I calculate the derivative at a point ?
>
> f(x):=diff(g(x),x);
> f(d/2) does not work when d is constant.
>
>
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