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Herbie automatically improves the error of floating point expressions. Visit our website for tutorials, documentation, and an online demo. Herbie has semi-regular releases once a year, maintains backwards compatibility, and uses standardized formats.


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

Herbie requires Racket 7.0 or later, and supports Windows, macOS, and Linux. Install it with:

raco pkg install --auto herbie

This will install a herbie binary to somewhere under ~/.racket. You can also download the source and run src/herbie.rkt directly.

Running Herbie

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

Herbie's input format is the Scheme-like FPCore; for example (1 + x) - x is written

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

You can see more examples in bench/. To use Herbie, run herbie shell and enter an FPCore expression:

$ herbie shell
Herbie 1.3 with seed 1866513483
Find help on, exit with Ctrl-D
herbie> (FPCore (x) (- (+ 1 x) x))
(FPCore (x) ... 1)

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

Besides shell, Herbie also has a web interface, and can be run in batch mode on files with the improve and report commands. Consult the documentation. for more.

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 development goals.

Running Tests

Herbie has unit tests for basic functionality, though coverage is far from complete. You can run the test suite by downloading the source code, changing to the source code directory, and running:

make install
raco test src/

Herbie also contains a large benchmark suite drawn from open source projects, examples from users, and numerical analysis textbooks. This suite is found in bench/. The full test can be run with

herbie report bench/ report/

You may see warnings; these are expected. The output is HTML files in report/. This full test can take a few hours to run. We often test Herbie on basic but representative examples with:

herbie report bench/hamming/ graphs/

This takes approximately 10 minutes.

Historic and nightly test results are collected on

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