Dear all,

I am glad to report a new version of BifurcationKit.jl (actually two in a row). Compared to the previous one, axed on periodic orbits, emphasis was put on codim 2 bifurcations, continuation, and their normal forms. More precisely,

- I re-wrote the interface to shooting problems to make the use of time steppers other than DifferentialEquations’ones simpler
- I re-wrote the interface of the predictor step to allow the easier development of new class of predictors. As a by-product, you can now change the underlying dot product in pseudo-arclength continuation. This is especially useful in FEM. This is shown in action in the new tutorial based on
`ApproxFun.jl`

- I added a simple tutorial based on ModelingToolkit

For codim 2:

- I added the detection of all codim 2 bifurcations which works in any dimension, sparse, dense, matrix-free etc. We are not many in this club
- I added the computation of the Bogdanov-Takens normal form, the cusp one and the bautin one.
- You can branch from these bifurcations to Hopf / Fold curves
- This is shown at work in an ODE tutorial, this one exhibits all codim 2 bifurcations so it is a nice “benchmark”.
- this is also shown for a 2d PDE tutorial which is the Ginzburg-Landau equation.
- this is also shown for a 1d PDE Langmuir which is the Ginzburg-Landau equation.

I hope some of you will find it useful.

Feel free to suggest improvements, design choices,… Also, do not hesitate to open issues if the docs are not clear enough.

Bests,