Simscape - Transient initialization vs Transient Solve

According to the Workflow presented here, Transient Initialization and Transient Solve are the last phases of Simscape Simulation.

Quoting from this source:

"Transient initialization fixes all dynamic variables and solves for algebraic variables and derivatives of dynamic variables [...]. Finally, the Simscape solver performs transient solve of the system of equations[...]. The solver continues to perform the simulation according to the results of the transient solve until the solver encounters an event, such as a zero crossing or discontinuity".

It is not clear to me why the solver switches back to "Transient Initialization" only in case of events, and not after each integration step.

In my understanding, each integration step of "Transient Solve" computes only the new values of the dynamic variables; than a new "Transient Initialization" should be required in order to compute the new values for algebraic variables and derivatives of dynamic variables.

To sum up: why does "Transient Initialization" kick in only after events, and not after each intergration step?

Answer 1

[David John]

The transient solve also solves for the algebraic variables. At an event, we re-initialize in order to handle possible jumps in variables that are due to the event.