## General¶

Q: What is the Hybrid Symbolic-Numeric Framework in ANDES?

A: It is a modeling and simulation framework that uses symbolic computation for descriptive modeling and code generation for fast numerical simulation. The goal of the framework is to reduce the programming efforts associated with implementing complex models and automate the research workflow of modeling, simulation, and documentation.

The framework reduces the modeling efforts from two aspects: (1) allowing modeling by typing in equations, and (2) allowing modeling using modularized control blocks and discontinuous components. One only needs to describe the model using equations and blocks without having to write the numerical code to implement the computation. The framework automatically generate symbolic expressions, computes partial derivatives, and generates vectorized numerical code.

## Modeling¶

A: Lines can be switched out and in by using Toggler. See the example in cases/kundur/kundur_full.xlsx. One does not need to manually trigger a Jacobian matrix rebuild because Toggler automatically triggers it using the new connectivity status.