Today we are very pleased to announce the release of Chebfun Version 5.

### What v5 represents

Chebfun Version 5 is a complete rewrite of the Chebfun code and a transition from an svn repository at Oxford to a public repository and issue tracker at GitHub. We are a fully open source project. We invite all our users to learn more and get involved.

The main purpose of the code rewrite has been greater modularity, clarity, and consistency, to make it easier for new developers to get involved and new variations to be explored and new features to be added. A completely new web site has also been created.

### New features

• A single email address help@chebfun.org for all queries
• Powerful new Chebfun2/roots for bivariate rootfinding
• Big speedups of conv, polyfit, abs, inv, and pde15s
• New commands leg2cheb, cheb2leg
• Algorithms based on Chebyshev points of the first kind
• A Chebfun constructor option 'equi' for equispaced data
• A 'periodic' option for Fourier instead of Chebyshev
• Ultraspherical spectral methods for ODEs
• epslevel estimates of accuracy, still under development

### We welcome new developers

The release of June 21, 2014 is a beta release, and Chebfun v5 is far from perfect. We hope users will enjoy working with it and will report bugs and suggestions—ideally at Github, or alternatively to help@chebfun.org. The last three bullet points above, in particular, are very much under development and are expected to evolve significantly in the next year.