Gleichungen
Zweck des Abschnitts equations in einer Komponentendatei ist die Festlegung der mathematischen Beziehungen zwischen den Variablen, Parametern, Ein- und Ausgängen der Komponente, der Simulationszeit und den Zeitableitungen jeder dieser Entitäten.
Analog dazu dient der Abschnitt equations in einer Domänendatei dazu, die mathematischen Beziehungen zwischen den Across-Variablen, Parametern und Zwischengliedern der Domäne herzustellen. Domänengleichungen werden auf die Knoten des entsprechenden Domänentyps übertragen.
Die Syntax von Komponenten- und Domänengleichungen ist identisch. Unter Defining Component Equations finden Sie allgemeine Informationen zum Schreiben von Gleichungen in der Simscape™-Sprache. Der Abschnitt Domain Equations enthält speziell auf Domänengleichungen bezogene Informationen.
Sprachsyntax
assert | Program customized run-time errors and warnings |
delay | Return past value of operand |
der | Return time derivative of operand |
equations | Define component or domain equations |
function | Reuse expressions in component equations and in member declarations of domains and components |
if | Specify conditional equations, assignments, annotations, and conditional sections in component files |
.if | Perform element-wise conditional operations with array-type predicates (Seit R2023b) |
integ | Perform time integration of expression |
intermediates | Define intermediate terms for use in equations |
scatteredlookup | Return value based on interpolating unstructured set of data points (Seit R2023a) |
tablelookup | Return value based on interpolating set of data points |
time | Access global simulation time |
value | Convert variable or parameter to unitless value with specified unit conversion |
Themen
- Defining Component Equations
The purpose of the
equationssection in a component file is to establish the mathematical relationships between the variables, parameters, inputs, and outputs of the component, the simulation time, and the time derivatives of each of these entities. - Simple Algebraic System
This example shows implementation for a simple algebraic system.
- Use Simulation Time in Equations
This example shows how you can access global simulation time from the equation section.
- Using Conditional Expressions in Equations
You can specify conditional expressions in equations or conditional assignments to intermediates by using
ifand.ifstatements. - Using Intermediate Terms in Equations
Textbooks often define certain equation terms in separate equations, and then substitute these intermediate equations into the main one.
- Using Lookup Tables in Equations
You can use the
tablelookupfunction in theequationssection of the Simscape file to interpolate input values based on a set of data points in a one-dimensional, two-dimensional, three-dimensional, or four-dimensional table. - Programming Run-Time Errors and Warnings
Use the
assertconstruct to implement run-time error and warning messages for a custom block. - Initial Equations
Specify additional equations to be executed during model initialization only.
- Simscape Functions
Use Simscape functions to reuse expressions in equations and member declarations of multiple components.
- Import Symbolic Math Toolbox Equations
Example of using Symbolic Math Toolbox™ software to solve the physical equations, generate code in the format appropriate for the Simscape language equation section, and incorporate the generated code into the equation section of a component file.
- Domain Equations
Specify additional equations to propagate to all the components that have nodes of the corresponding domain type.
