Re: [Maxima-discuss] is(equal(op(f(x,y)), 'del)) -> unknown

[Barton W. <wi...@un...>]

I think you need to test for syntactic equality, not semantic equality. And you might need to head the setting of prederror too.  The user documentation for “equal” has some details.


Tests for semantic equality

(%i5)  block([prederror : false], is(equal((x+1)^2, x^2+2*x+1)));
(%o5) true


(%i1)   block([prederror : true], is(equal(op(f(x,y)), 'del)));
Unable to evaluate predicate equal(f,del)

(%i2)  block([prederror : false], is(equal(op(f(x,y)), 'del)));
(%o2) unknown

Test for syntactic equality

(%i3)  block([prederror : true], is(op(f(x,y))= 'del));
(%o3) false

(%i4)  block([prederror : false], is(op(f(x,y))= 'del));
(%o4) false

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From: Eduardo Ochs<mailto:edu...@gm...>
Sent: Saturday, September 30, 2023 7:42 AM
To: <max...@li...><mailto:max...@li...>
Subject: [Maxima-discuss] is(equal(op(f(x,y)), 'del)) -> unknown

Non-NU Email

Hi list,

if I run these expressions in the REPL

  is(equal(op(del(w)), 'del));
  is(equal(op(f(x,y)), 'del));
  if is(equal(op(del(w)), 'del)) then "yes" else "no";
  if is(equal(op(f(x,y)), 'del)) then "yes" else "no";

I get this:

  (%i1) is(equal(op(del(w)), 'del));
  (%o1)                                true
  (%i2) is(equal(op(f(x,y)), 'del));
  (%o2)                               unknown
  (%i3) if is(equal(op(del(w)), 'del)) then "yes" else "no";
  (%o3)                                 yes
  (%i4) if is(equal(op(f(x,y)), 'del)) then "yes" else "no";
  (%o4)                     if unknown then yes else no
  (%i5)

The is(equal(op(o),'del)) returns "true", "false", or "unknown". How
do I replace it by something that converts the "unknown"s to "false"s?

  Thanks in advance!
    Eduardo Ochs
    http://anggtwu.net/eev-maxima.html<https://urldefense.com/v3/__http:/anggtwu.net/eev-maxima.html__;!!PvXuogZ4sRB2p-tU!GNaxwGVTipE82T-sI-zLuEl2633SKjs92BGP_Vw42MrMWqrXI91q9muM2zJpiIVrnnxBUAIFbohKpv2hRoI$>