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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)
Next: Identifiers, Previous: Introduction to Expressions, Up: Expressions [Contents][Index]