Executable interval and analytic enclosures #
Rational interval arithmetic and exponential, logarithmic, and trigonometric kernels, with proofs
that their computed endpoints enclose the exact real values. Concrete numerical formats can refine
these bounds until they determine a rounding decision. Constants caches proved integer bounds of
π / 2, 2 / π and log 2 at every precision. The binary interchange kernels read them: sine and
cosine reduction, exponential reduction, generated configurations, the certified power and
Model.pi. The exact comparators and BinaryGrid.log compute their own π / 4 and log 2.
ArgumentReduction reduces an argument m * 2 ^ e modulo π / 2 by the method of Payne and Hanek,
from a window of the cached 2 / π, with a proved bound on the error of its remainder.
Interval also accepts arbitrary endpoint representations. Partial outward-rounding contracts
separate the common ordered-field enclosure proofs from a format's range and encoding.
Interval.Expr composes these operations into real expressions, and its rational and integer
binary-grid backends share one containment theorem and adaptive subdivision checker.