[Maxima-bugs] [ maxima-Bugs-1052382 ] assume hard to use programmatically

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Bugs item #1052382, was opened at 2004-10-22 12:33
Message generated for change (Settings changed) made by robert_dodier
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>Category: Lisp Core - Assume
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Stavros Macrakis (macrakis)
Assigned to: Nobody/Anonymous (nobody)
Summary: assume hard to use programmatically

Initial Comment:
   assume(r>0 and r<1)

works fine.

However, if I have a function

   withassume(pred,expr) :=
      ( assume(pred), expand(expr) );

you get

    withassume(r>0 and r<1, abs(r))
       => ERROR: can't eval predicate r>0

Quoting doesn't help:

     withassume('(r>0 and r<1), abs(r)) => error
     withassume('('(r>0) and '(r<1)), abs(r)) => error
     withassume(('"and")(r>0) and '(r<1)), abs(r)) => error
     withassume('("and")(r>0) and '(r<1)), abs(r)) => error

There is a workaround, however:

   withassume(pred,expr) :=
      ( apply('assume,[pred]), expand(expr) );

You still have to quote the argument, but it works now:

    withassume('(r>0 and r<1), abs(r)) => r

Alternatively, you can use the noun form of AND:

    withassume('("and")(r>0,r<1),abs(r)) => r

Yuck in both cases.

------------------------------
Discussion

The underlying problem is that "is", "assume",
"forget", etc. quote their arguments then depend on
their own little idiosyncratic evaluator....

Also that noun-form logical connectives (and, or, if)
aren't really supported.


Maxima version: 5.9.0.9beta2
Maxima build date: 10:50 7/27/2004
host type: i686-pc-mingw32
lisp-implementation-type: Kyoto Common Lisp
lisp-implementation-version: GCL 2.6.3


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You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1052382&group_id=4933