|Program customized run-time errors and warnings|
|Return past value of operand|
|Return time derivative of operand|
|Define component equations|
|Reuse expressions in component equations and in member declarations of domains and components|
|Perform time integration of expression|
|Define intermediate terms for use in equations|
|Return value based on interpolating set of data points|
|Access global simulation time|
|Convert variable or parameter to unitless value with specified unit conversion|
The purpose of the equation section is to establish the mathematical relationships among a component’s variables, parameters, inputs, outputs, time and the time derivatives of each of these entities. The equation section of a Simscape™ file is executed throughout the simulation.
This example shows implementation for a simple algebraic system.
This example shows how you can access global simulation time from the equation section.
You can specify conditional equations by using
Textbooks often define certain equation terms in separate equations, and then substitute these intermediate equations into the main one. For example, for fully developed flow in ducts, the Darcy friction factor can be used to compute pressure loss:
You can use the
tablelookup function in the
section of the Simscape file to interpolate input values based on a set of data points in a
one-dimensional, two-dimensional, or three-dimensional table. This functionality is similar to
that of the Simulink® and Simscape Lookup Table blocks. It allows you to incorporate table-driven modeling directly
in your custom block, without the need of connecting an external Lookup Table block to your
assert construct to implement run-time error and warning messages
for a custom block. In the component file, you specify the condition to be evaluated, as well
as the error message to be output if this condition is violated. When the custom block based
on this component file is used in a model, it will output this message if the condition is
violated during simulation. The optional
Action attribute of the
assert construct specifies whether simulation stops when the predicate
condition is violated, continues with a warning, or ignores the violation.
Use Simscape functions to reuse expressions in equations and member declarations of multiple components.
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.