Inconsistencies in noun/verb

[rtoy]

Imported from SourceForge on 2024-07-04 14:06:46 Created by macrakis on 2003-03-28 19:58:07 Original: https://sourceforge.net/p/maxima/bugs/280

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-- nounify(diff) displays as derivative when display2d is true, and diff when display2d is false.

-- In some cases, the noun form is spelled differently from the verb form. This can be handy, though it is confusing. For example, "IF" has a convenient noun form, COND, so you can write COND(a,b,c) without getting an error ("unable to evaluate predicate").
However, though the noun form of DIFF displays as DERIVATIVE, when Maxima reads in DERIVATIVE, it in fact uses the verb form DIFF. Example:

if(1<2,a,b) => a Verb form nounify("IF") => COND (%cond) (nounify("IF"))(a,b) Noun form cond(1<2,a,b) => cond(1<2,a,b) Noun form part(_,0) => cond Noun form

diff(x^2,x) => 2*x Verb form nounify('diff) => DERIVATIVE (%derivative) (nounify('diff))(x^2,x) Noun form derivative(x^2,x) => 2*x Verb form part(_,0) => diff Verb form

-- apply_nouns is documented, but nowhere defined

-- Noun/verb behavior of operators like "+" and "IF" is messed up:

-- ev( (' "+")(x,x), nouns) returns +(x,x) instead of 2*x.
This is because (' "+")(x,y) gives ((&+) x y). It should give the same thing as (nounify("+"))(x,y), namely ((% mplus simp) x y).

-- Similarly for "IF".

-- I haven't tested thoroughly, but there seem to be similar confusions for "DO"/MDO, ":"/SETQ, etc.

[rtoy]

Imported from SourceForge on 2024-07-04 14:06:47 Created by macrakis on 2003-03-28 22:34:31 Original: https://sourceforge.net/p/maxima/bugs/280/#a1d1

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Logged In: YES user_id=588346

I spoke too soon about the "convenience" of COND.

verbify(COND) and verbify(nounify(COND)) give %COND rather than MCOND as they should, so COND(a,b,c) doesn't get an error because it has nothing to do with IF/MCOND.

[rtoy]

Imported from SourceForge on 2024-07-04 14:06:50 Created by macrakis on 2003-08-30 21:31:01 Original: https://sourceforge.net/p/maxima/bugs/280/#2de0

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Logged In: YES user_id=588346

The semantics of noun/verb are pretty unclear.

In the case of trig functions, verbs return floating-point results: (verbify('sin))(0) => 0.0; but not for elementary arithmetic: (verbify('"+"))(0,4) => 4.

In the case of trig functions, nouns simplify: (nounify('sin))(% pi) => 0; but not for elementary arithmetic: (nounify('"+")) (4,5) => PLUS(4,5).

[rtoy]

Imported from SourceForge on 2024-07-04 14:06:54 Created by macrakis on 2003-12-21 20:43:34 Original: https://sourceforge.net/p/maxima/bugs/280/#c647

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Logged In: YES user_id=588346

In general, the noun/verb forms for infix operators are screwed up:

I was going to write up a detailed analysis, but it is too much of a mess. Here is a transcript showing some of the peculiar cases:

(C17) ?print([">",verbify(">"),nounify(">")]);

((MLIST SIMP) &> MGREATERP %GREATERP) (D17) [>, ">", GREATERP] (C18) string(%); (D18) [">",?MGREATERP,GREATERP] (C19) is(nounify(">")=GREATERP); (D19) FALSE (C20) is(nounify(">")=greaterp); (D20) FALSE (C21) ?print(["+",verbify("+"),nounify("+")]);

((MLIST SIMP) &+ MPLUS %PLUS) (D21) [+, "+", PLUS] (C22) string(%); (D22) ["+",?MPLUS,PLUS] (C23) ["+"(a,b),'"+"(a,b),?MPLUS(a,b),PLUS(a,b)]; (D23) [b + a, PLUS(a, b), b + a, PLUS(a, b)] (C24) map(op,%); (D24) [+, PLUS, +, PLUS] (C25) ?print(%);

((MLIST SIMP) &+ %PLUS &+ $PLUS) (D25) [+, PLUS, +, PLUS] (C26)

[rtoy]

Imported from SourceForge on 2024-07-04 14:06:57 Created by robert_dodier on 2004-11-25 18:02:15 Original: https://sourceforge.net/p/maxima/bugs/280/#1d70

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Description of "apply_nouns" has been struck from doc/info/Simplification.texi.

[rtoy]

Imported from SourceForge on 2024-07-04 14:07:01 Created by robert_dodier on 2006-07-06 05:42:02 Original: https://sourceforge.net/p/maxima/bugs/280/#3366

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• labels: --> Lisp Core