Herbie synthesizes floating-point programs from real-number programs, automatically handling simple numerical instabilities. Visit our website for tutorials, documentation, and an online demo.

Current Status

Herbie can improve the accuracy of many real-world programs, and is used by scientists in many disciplines. It has lead to two patches (for complex square roots and trigonometric functions), in math.js an open-source mathematics library. Herbie has semi-regular releases twice a year, maintains backwards compatibility, and uses standardized formats.

Helping Out

Herbie development is organized on our mailing list where we discuss work in progress and announce major improvements. Email us to get involved!

We use Github and Trello to organize some development goals Our test results are archived.

Installing

For full details on installing Herbie, please see the tutorial.

Herbie requires Racket 6.3 or later, and supports Linux and OS X. Install it with:

raco pkg install herbie

This will install a herbie binary to somewhere in your home directory. You can also run src/herbie.rkt directly instead of using the herbie command, for example if you'd like to download the source directly instead of through the package manager.

Running Herbie

For full details on running Herbie, please see the tutorial.

Herbie's input is a Scheme-based language called FPCore; you can several examples in bench/. For example, consider this simple expression:

(FPCore (x)
  (- (+ 1 x) x))

Run Herbie from the top-level directory of the repo, and enter the cancellation test:

$ herbie shell
Seed: #(1046809171 2544984934 1871826185 4237421819 4093186437 162666889)
herbie> (FPCore (x) (- (+ 1 x) x))
(FPCore (x) 1)

The output is Herbie's improved, more-accurate expression, in this case the constant 1.

Besides the shell, Herbie also has a web interface, and can run on files of FPCore expressions with the improve and report commands. Consult the documentation. for more.

Running Tests

Herbie contains unit tests to test basic functionality, though coverage is far from complete. You can run the test suite with:

raco test src/

Herbie also contains a large integration suite from open source projects, examples emailed to the developers, and from numerical analysis textbooks. This suite is found in bench/. The full test can be run with

herbie report bench/

This full test can take several hours to run. We often test Herbie on basic but representative examples with:

herbie report bench/hamming/

This takes approximately 15 minutes.

Test results are collected on uwplse.org. If you have an account on this server, you can publish your test results with

make publish