Maxima Function
is (expr)
Attempts to determine whether the predicate expr
is provable from the facts in the assume
database.
If the predicate is provably true
or false
,
is
returns true
or false
, respectively.
Otherwise, the return value is governed by the global flag prederror
.
When prederror
is true
,
is
complains with an error message.
Otherwise, is
returns unknown
.
ev(expr, pred)
(which can be written expr, pred
at the interactive prompt)
is equivalent to is(expr)
.
Examples:
is
causes evaluation of predicates.
(%i1) %pi > %e; (%o1) %pi > %e (%i2) is (%pi > %e); (%o2) true
is
attempts to derive predicates from the assume
database.
(%i1) assume (a > b); (%o1) [a > b] (%i2) assume (b > c); (%o2) [b > c] (%i3) is (a < b); (%o3) false (%i4) is (a > c); (%o4) true (%i5) is (equal (a, c)); (%o5) false
If is
can neither prove nor disprove a predicate from the assume
database,
the global flag prederror
governs the behavior of is
.