127 lines
2.5 KiB
Python
127 lines
2.5 KiB
Python
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from sympy.assumptions import Predicate
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from sympy.multipledispatch import Dispatcher
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class PrimePredicate(Predicate):
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"""
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Prime number predicate.
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Explanation
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===========
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``ask(Q.prime(x))`` is true iff ``x`` is a natural number greater
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than 1 that has no positive divisors other than ``1`` and the
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number itself.
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Examples
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========
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>>> from sympy import Q, ask
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>>> ask(Q.prime(0))
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False
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>>> ask(Q.prime(1))
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False
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>>> ask(Q.prime(2))
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True
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>>> ask(Q.prime(20))
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False
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>>> ask(Q.prime(-3))
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False
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"""
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name = 'prime'
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handler = Dispatcher(
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"PrimeHandler",
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doc=("Handler for key 'prime'. Test that an expression represents a prime"
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" number. When the expression is an exact number, the result (when True)"
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" is subject to the limitations of isprime() which is used to return the "
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"result.")
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)
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class CompositePredicate(Predicate):
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"""
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Composite number predicate.
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Explanation
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===========
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``ask(Q.composite(x))`` is true iff ``x`` is a positive integer and has
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at least one positive divisor other than ``1`` and the number itself.
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Examples
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========
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>>> from sympy import Q, ask
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>>> ask(Q.composite(0))
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False
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>>> ask(Q.composite(1))
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False
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>>> ask(Q.composite(2))
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False
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>>> ask(Q.composite(20))
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True
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"""
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name = 'composite'
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handler = Dispatcher("CompositeHandler", doc="Handler for key 'composite'.")
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class EvenPredicate(Predicate):
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"""
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Even number predicate.
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Explanation
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===========
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``ask(Q.even(x))`` is true iff ``x`` belongs to the set of even
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integers.
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Examples
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========
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>>> from sympy import Q, ask, pi
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>>> ask(Q.even(0))
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True
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>>> ask(Q.even(2))
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True
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>>> ask(Q.even(3))
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False
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>>> ask(Q.even(pi))
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False
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"""
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name = 'even'
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handler = Dispatcher("EvenHandler", doc="Handler for key 'even'.")
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class OddPredicate(Predicate):
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"""
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Odd number predicate.
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Explanation
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===========
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``ask(Q.odd(x))`` is true iff ``x`` belongs to the set of odd numbers.
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Examples
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========
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>>> from sympy import Q, ask, pi
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>>> ask(Q.odd(0))
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False
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>>> ask(Q.odd(2))
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False
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>>> ask(Q.odd(3))
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True
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>>> ask(Q.odd(pi))
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False
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"""
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name = 'odd'
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handler = Dispatcher(
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"OddHandler",
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doc=("Handler for key 'odd'. Test that an expression represents an odd"
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" number.")
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)
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