pne_callback_default

pne_callback_default(k, nx, cx, px, s, opt)
pne_callback_default() - Default callback function for pnes_master().
[NX, CX, S] = PNE_CALLBACK_DEFAULT(K, NX, CX, PX, S, OPT)

Default callback function used by PNES_MASTER, collects the results
and optionally plots the continuation curve. Always registered with
priority 0. See PNE_REGISTER_CALLBACKS for details.

This callback uses the 'default' field of the callback state (cbs)
for its data.

Inputs:
    K - continuation step iteration count
    CX - current state, corresponding to most recent successful step
         with the following fields:
        x_hat - solution vector from predictor
        x - solution vector from corrector
        z - normalized tangent vector
        default_step - default step size
        default_parm - handle to function implementing parameterization
            used by default
        this_step - step size for this step only
        this_parm - handle to function implementing parameterization
            used for this step only
        step - current step size
        parm - handle to function implementing current parameterization
        events - event log, struct array, see PNE_DETECT_EVENTS for details
        cbs - callback state, callback functions may add fields containing
            any information the function would like to pass from
            one invokation to the next, taking care not to step on fields
            being used by other callbacks, such as the 'default' field
            used by this default callback
        efv - cell array of event function values
    NX - next state (corresponding to proposed next step), struct with
         (same structure as CX and PX)
    PX - previous state, corresponding to last successful step prior to CX
         (same structure as CX and NX)
    S - container struct for various flags, etc., with fields:
        done - termination flag, 1 => terminate, 0 => continue
        done_msg - char array with reason for termination
        warmstart - struct with warm-start state to be passed to
            subsequent warm-started call to PNES_MASTER
        rollback - flag to indicate that the current step should be
            rolled back and retried with a different step size, etc.
        events - struct array listing events detected for this step,
            see PNE_DETECT_EVENTS for details
        results - current value of results struct whose fields are to be
            included in the OUTPUT struct returned by PNES_MASTER
    OPT - PNES_MASTER options struct

Outputs:
    (all are updated versions of the corresponding input arguments)
    CX - update values in this state if S.rollback is true,
        e.g. 'this_step' or 'this_parm'
    NX - update values in this state if S.rollback is false,
        e.g. user callback state ('cbs' field ), etc.
    S - struct for various flags, etc.
        done - can request termination by setting to 1
        done_msg - can set termination reason here
        warmstart - information can be added that can be used to
            start a new warm-started run, e.g. with updated FCN
        rollback - can request a rollback step, even if it was not
            indicated by an event function
        events - msg field for a given event may be updated
        results - updated results struct whose fields are to be
            included in the OUTPUT struct returned by PNES_MASTER

All callback functions, including this one, are called in three different
contexts, distinguished by the value of K, as follows:
(1) initial - called with K = 0, after initial corrector step,
        before 1st continuation step.
(2) iterations - called with K > 0, at each iteration, after
        predictor-corrector step
(3) final - called with K < 0, after exiting predictor-corrector loop,
        same as last iteration call, with negated K and updated PX, CX

User Defined PNE Callback Functions:
    The user can define their own callback functions which take
    the same form and are called in the same contexts as
    PNE_CALLBACK_DEFAULT. These are specified via OPT.callbacks which
    takes the same form as the MY_CBACKS input to PNE_REGISTER_CALLBACKS.