Tipps’n tricks

• Check the m2html documentation of pde2path functions for an overview.
• Check the Matlab pdetoolbox help/users guide, and the alphabetic function list.
• To load a previously saved structure p use p=loadp(pre,fname,name), or simply double click on a pXXX file. Then manipulate it (in case of ”load by click” perhaps after renaming or copying to a new variable name) and call, e.g., cont.
• Manipulate memory of a stored p-file by editing p.branch. For instance reset memory: p.branch = []; or append to branches (check that the point ordering fits): p.branch = [p.branch;p1.branch];
• If pde2path indicates a bifurcation (due to a sign change of det(A)), but no eigenvalue of ∂_uG crosses the origin, consider increasing p.neig. Check whether this has an effect using the utility function sgndetA(p,neig). Also check p.eigref = ′sr′, which computes the eigenvalues with smallest real part, but is much slower than the default p.eigref = 0.
• For bifurcations from an explicitly known (parameter-dependent) equilibrium u₀(λ), consider shifting u to v = u−u₀(λ) for faster and more robust numerical computations.
• to be continued ...

octave

For users who have access to the Matlab pdetoolbox but prefer octave over Matlab we provide a compatibility mode with (currently) very restricted functionality. For this, in octave call path(path-to-pdetoolbox,path); and after setting the path to p2plib, call, e.g., path(’pde2pathhome/octcomp’,path); as the functions in octcomp must mask the functions in p2plib. In fact, in octcomp we only reset p2interpol.m and plotsol.m since in octave only mesh-plotting (plotstyle 1) works reliably.

With these changes the demos bratu and ac work (where it is useful to turn off octave pagination with more), while the other demos require some more adaptions. In particular there currently is no numjac in octave. However, quick adaptions should be no problem for expert users. Sometimes it is helpful to compare Matlab’s performance with octave.

FAQ

(Hopefully) coming soon ..