generate::Simscape

Generate Simscape equation

Use only in the MuPAD Notebook Interface.

This functionality does not run in MATLAB.

Syntax

generate::Simscape(e, <NoWarning>)

Description

generate::Simscape(e) generates Simscape™ code for the MuPAD® expression e.

Simscape software extends the Simulink® product line with tools for modeling and simulating multidomain physical systems, such as those with mechanical, hydraulic, pneumatic, thermal, and electrical components. Unlike other Simulink blocks, which represent mathematical operations or operate on signals, Simscape blocks represent physical components or relationships directly. With Simscape blocks, you build a model of a system just as you would assemble a physical system. For more information about Simscape software, see Simscape.

You can extend the Simscape modeling environment by creating custom components. When you define a component, use the equation section of the component file to establish the mathematical relationships among a component's variables, parameters, inputs, outputs, time, and the time derivatives of each of these entities. MuPAD and Simscape software let you perform symbolic computations and use the results of these computations in the equation section. The generate::Simscape function translates the results of symbolic computations to Simscape language equations.

generate::Simscape returns a Simscape formatted string representing an expression, equation, list of expressions or equations, or a matrix.

generate::Simscape converts the identifier t to the variable time in the resulting Simscape code. However, the name t of a function call does not change during conversion. See Example 1 and Example 2.

generate::Simscape converts any derivative with respect to the variable t to the Simscape notation x.der, where x is the time-dependent variable. See Example 3.

generate::Simscape assumes that the type of converted data is double. See Example 4.

When generating Simscape code for a matrix, the generator produces a dense matrix. See Example 5.

Use the generate::optimize function to optimize the MuPAD code before converting it to the Simscape syntax. See Example 6.

generate::Simscape converts piecewise expressions to Simscape code by using the if statements. See Example 7.

The equation section of a Simscape component file supports a limited number of functions. For details and the list of supported functions, see Simscape equations. If a symbolic equation contains the functions that are not available in the equation section of a Simscape component file, generate::Simscape cannot correctly convert these equations to Simscape equations. Such expressions do not trigger an error. The following types of expressions are prone to invalid conversion:

  • Expressions with infinities

  • Expressions that contain programming structures, such as loops, coditional statements (except for the if statement), and map function calls

  • Expressions that contain intervals, sets, and lists

To display generated Simscape code on screen, use the print function. To remove quotation marks and to expand special characters like line breaks and tabs, use the printing option Unquoted. If a generated code line is longer than the TEXTWIDTH setting, the print function breaks that line into several shorter lines. The inserted line continuation character (\) is not valid in Simscape. To avoid inserting line continuation characters, increase the TEXTWIDTH setting or use the fprint function to write generated code to a file.

To write generated Simscape code to a file, use the fprint function with the Unquoted option. See Example 8.

The NoWarning option lets you suppress warnings. See Example 2.

Examples

Example 1

The generate::Simscape function replaces all instances of the MuPAD identifier t with the variable time. For example, convert the following equation to the Simscape equation:

e := A*sin(w*t) + B*cos(w*t) = 0:
print(Unquoted, generate::Simscape(e))
  B*cos(time*w)+A*sin(time*w) == 0.0;

Example 2

The generate::Simscape function does not change the function name t in function calls:

print(Unquoted, generate::Simscape([t(), t(0), t(x)]))
Warning: Function 't' is not verified to be a valid Simscape function.
Warning: Function 't' is not verified to be a valid Simscape function.
Warning: Function 't' is not verified to be a valid Simscape function.
  t();
  t(0.0);
  t(x);

This example produces a few identical warnings. If you started using generate::Simscape recently, warnings can help you identify potential issues in the converted code. If you want to suppress warnings, use the NoWarning option:

print(Unquoted, generate::Simscape([t(), t(0), t(x)], NoWarning))
  t();
  t(0.0);
  t(x);

Example 3

When generating Simscape code, the generate::Simscape function converts the derivatives with respect to the variable t to the Simscape notation x.der. Here x is the time-dependent variable. For example, generate the Simscape code for the equation e that has two time-dependent variables:

e := x'(t) + diff(y(t), t) + 2*x + 5 = 0:
print(Unquoted, generate::Simscape(e))
  x*2.0+x.der+y.der+5.0 == 0.0;

Example 4

By default, Simscape stores all numeric values as double-precision floating-point values. In accordance with this default data type, generate::Simscape converts the elements of expressions, equations, and matrices to the double format:

print(Unquoted, generate::Simscape(x^2 + y/3 + 1/6))
  y*(1.0/3.0)+x^2+1.0/6.0;

Example 5

generate::Simscape can generate Simscape code for a MuPAD matrix. In contrast to generate::MATLAB (which produces sparse matrices), the Simscape code generator produces dense matrices:

A:= matrix([[1, 0, 0],[0, 0, 1]]):
print(Unquoted, generate::Simscape(A))
  [
  1.0 0.0 0.0
  0.0 0.0 1.0
  ];

Example 6

The generate::Simscape function does not optimize your code:

print(Unquoted,
      generate::Simscape([x = a + b, y = (a + b)^2])):
  x == a+b;
  y == (a+b)^2;

You can use the generate::optimize function before converting your MuPAD code to Simscape syntax. For example, this function can reduce the number of operations by finding common subexpressions:

print(Unquoted,
      generate::Simscape(
          generate::optimize([x = a + b, y = (a + b)^2])
      )):
  x == a+b;
  y == x^2;

Example 7

The generate::Simscape function also accepts piecewise expressions. The function uses if statements when generating Simscape code for piecewise expressions. For example, the Fourier transform of the following expression is a piecewise function:

FT := fourier(exp(-abs(x)*abs(t))*sin(t)/t, t, s)

generate::Simscape converts this result to a valid Simscape expression:

print(Unquoted, generate::Simscape(FT))
  if (x ~= 0.0),
    -atan((s-1.0)/abs(x))+atan((s+1.0)/abs(x));
  else
    NaN;
  end

Example 8

To create a text file with a Simscape formatted string representing a symbolic expression, use the fprint command:

e := x'(t) + 2*x + 5 = 0:
fprint(Unquoted, Text, "eqn.txt", generate::Simscape(e))

If the file eqn.txt already exists, fprint replaces the existing Simscape code with the converted symbolic expression. You can open and edit the resulting text file.

Parameters

e

An expression, equation, list of equations, or a matrix

Options

NoWarning

Suppress warnings.

Return Values

generate::Simscape returns a string containing Simscape code. In case of invalid conversion, the returned value is an arbitrary string.

See Also

MuPAD Functions

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