[EMAIL PROTECTED] writes:
> Dear Dr. Gabriel Dos Reis , how are you
> I find a bug about open axiom
> a := 28 - 8*sqrt(6)
> a < 0 will return true
> in fact it should be false
> Why < is wrong? What cause the problem?
> Thanks!
> Weiqin Ma
It's not really a bug.
a := 28 - 8*sqrt(6)
is an "AlgebraicNumber" and for reasons I do not quite understand,
AlgebraicNumber does not have mathematical "<". (It does have mathematical "="
though.) It only uses an internal hash ordering, in fact, the ordering is the
same as in EXPR INT.
Thus, do not be surprised that axiom says:
(1) -> %pi < %e
(1) true
Type: Boolean
Fortunately, axiom has an extremely powerful domain "RealClosure", which does
what you need:
(2) -> R ==> RECLOS FRAC INT
Type: Void
(3) -> a := 28 - 8*sqrt(6, 2)$R
+-+
(3) - 8\|6 + 28
Type: RealClosure Fraction Integer
(4) -> a < 0
(4) false
Type: Boolean
Martin
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