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Maxima distinguishes between operators which are "nouns" and operators which are
"verbs". A verb is an operator which can be executed. A noun is an operator
which appears as a symbol in an expression, without being executed. By default,
function names are verbs. A verb can be changed into a noun by quoting the
function name or applying the nounify
function. A noun can be changed
into a verb by applying the verbify
function. The evaluation flag
nouns
causes ev
to evaluate nouns in an expression.
The verb form is distinguished by a leading dollar sign $
on the
corresponding Lisp symbol. In contrast, the noun form is distinguished by a
leading percent sign %
on the corresponding Lisp symbol. Some nouns have
special display properties, such as 'integrate
and 'derivative
(returned by diff
), but most do not. By default, the noun and verb forms
of a function are identical when displayed. The global flag noundisp
causes Maxima to display nouns with a leading quote mark '
.
See also noun
, nouns
, nounify
, and
verbify
.
Examples:
(%i1) foo (x) := x^2; 2 (%o1) foo(x) := x
(%i2) foo (42); (%o2) 1764
(%i3) 'foo (42); (%o3) foo(42)
(%i4) 'foo (42), nouns; (%o4) 1764
(%i5) declare (bar, noun); (%o5) done
(%i6) bar (x) := x/17; x (%o6) bar(x) := -- 17
(%i7) bar (52); (%o7) bar(52)
(%i8) bar (52), nouns; (%o8) bar(52)
(%i9) integrate (1/x, x, 1, 42); (%o9) log(42)
(%i10) 'integrate (1/x, x, 1, 42); 42 / [ 1 (%o10) I - dx ] x / 1
(%i11) ev (%, nouns); (%o11) log(42)
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