In particular you might wish to do this:
for direction in [plus,minus] do print(limit(f(x),x,a,direction)
On the other hand I think that if you want to do
(defconstant $plus '$plus)
that may prevent anyone from reassigning
$PLUS.
And yes, most but not all commands in macsyma evaluate
all their arguments in a uniform fashion. The exceptions
include (I think) ev, some variants of display, solve.
It makes some usages of the commands neater, but at
the cost of non uniformity and sometimes forces people
who want the arguments evaluated to use apply or some
other technique.
RJF
Raymond Toy wrote:
>>>>>>"CY" == C Y <smustudent1@yahoo.com> writes:
>>>>>>
>
> CY> 3. Have the limit command treat the strings PLUS and MINUS specially,
> CY> regardless of their contents, and otherwise allow PLUS and MINUS to be
> CY> variables. Only drawbacks here are that PLUS and MINUS variables
> CY> couldn't be fed to Limit command, and need to train the limit command
> CY> to handle this case.
>
> I don't think this will work. By the time limit gets run, it only
> sees value of the fourth arg:
>
> (C1) plus:42;
>
> (D1) 42
> (C2) foo:'plus;
>
> (D2) PLUS
> (C3) limit(tan(x),x,%pi/2,foo);
>
> Ray
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