Is there an implementation of _rational_ interval arithmetic in Python?

Question

Is there an implementation of rational interval arithmetic in Python? This uses floats, not rationals.

If not, is there any implementation of rationals in Python that includes ±∞ ?

Answer 1

Sympy has intervals, rational numbers, and infinity. The Interval class is a subclass of the Set class.

# oo is the symbol for infinity
from sympy import Interval, oo, Rational

i1 = Interval(10, 15)
i2 = Interval(0, oo)
i3 = Interval(-5, -1)
# adding intervals
i4 = i1 + i3
i5 = i1 + i2
# interval with open end
i6 = Interval(Rational(1, 2), Rational(45, 3), left_open=True)

print 11 in i1 # True
print -1 in i1 # False
print 0 in i4 # False
print Rational(3, 2) in i6 # True
print oo in i2 # False
print i2.sup # oo (infinity)
print Rational(1, 2) in i6 # False
print i6.inf # 1/2

Answer 2

PyInterval now has rational interval arithmetic in Python feature.

From PyInterval Docs:

The interval package can be loaded into the Python interpreter with the statement which injects in the current namespace the interval class, a constant representing the mathematical infinity, and a module providing interval transcendental functions.

from interval import interval, inf, imath

interval[0, 2] * interval[4, inf]
interval([-inf, inf])