Rival is a library for evaluating real expressions to high precision.
Rival supports Racket 8.0+ and depends only on the standard math
library, including math/bigfloat.
Rival is easiest to use from its REPL:
$ racket -l rival
> (eval (sin 1e100))
-0.3723761236612767
> (set precision 1000)
> (eval (sin 1e100))
-0.3723761236612766882620866955531642957...
> (set precision 100)
> (define (f x) (- (sin x) (- x (/ (pow x 3) 6))))
> (eval f 1e-100)
8.3333333333333333333333333333237e-503
The full documentation describes the Racket API and the underlying interval library.
Rival provides a number of advanced features, which we believe makes Rival the state of the art real evaluation library:
- Support for all
math.hfunctions, including arithmetic, trigonometric, power, remainder, rounding, and even gamma functions. - Support for comparisons, conditionals, and boolean operations through boolean intervals
- Sound handling of domain errors through error intervals
- Fast and accurate mixed-precision assignments for evaluation
- Correct rounding
- Early exit using movability flags
- Well-tested soundness and robustness
Please file issues and submit patches on
Github. All code should be
formatted using raco fmt; you can set this up to happen on commit
with:
make hook
Additionally, all code must pass the automated tests, which you can run with:
raco test test.rkt
They also run in CI before merging. Finally, performance is a key metric for Rival; you can run the automated performance tests with:
racket -y time.rkt