Bugs item #1641498, was opened at 20070122 03:06
Message generated for change (Comment added) made by nobody
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Category: Lisp Core
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Barton Willis (willisbl)
Assigned to: Nobody/Anonymous (nobody)
Summary: Function "at" is overly cautious
Initial Comment:
Compare
(%i1) at(f(x), x = 0);
(%o1) f(0)
with
(%i2) at('integrate(f(t),t,0,x),x=0);
(%o2) at(integrate(f(t),t,0,x),x=0)
Given (%o1), it would seem consistent for (%o2) to
evaluate to 0. Declaring f to be anaylic doesn't
help:
(%i3) declare(f,analytic);
(%o3) done
(%i4) at('integrate(f(t),t,0,x),x=0);
(%o4) at(integrate(f(t),t,0,x),x=0)
Does Maxima ever use the declare analytic data?

Comment By: Nobody/Anonymous (nobody)
Date: 20071220 14:06
Message:
Logged In: NO
At the botton of this problem is the difference between two types of
arguments: Some of them are to be considered as a
constant while other not.
Example: Here in integrate(f(t),t,0,x) x should be considered as a
constant argument that is: we can substitute before
evaluating the integration.
But in diff(f(x*y),x) at x=0. x should not be considered as a constant
argument, so in this case we need first to compute the
diff and then substitute.
This can be accomplish in a case by case, or indicating the type
(constant or not constant of the argument).

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