Simulink Reference

Limitations with Complex Numbers

Complex numbers and operations are supported in Embedded MATLAB Function blocks with the following exceptions:

• The first use of a variable that is later assigned a complex result must also be complex. For example,

• X = 3;
      .
      .
      .
  X = 4 + 5i;
  

• fails because X is not defined as a complex variable by its first assignment. However,

  • X = 3 + 0i;
        .
        .
        .
    X = 4 + 5i;
    

  succeeds because X is defined as a complex variable in its first assignment.

• Even if the imaginary part is zero, if the result might be complex, Embedded MATLAB will treat it as complex. For example, although

• X = ifft(fft(Y));
  

• yields a real answer, Embedded MATLAB assumes that the function ifft might return a complex result. The workaround is to use the real function:

  • X = real(ifft(fft(Y)));
    

• Inheritance of variable type from a complex-valued Simulink signal does not make the variable a complex number. Input (argument) variables are assumed to be noncomplex unless they are specified complex in the Model Explorer.

Limitations on Indexing Operations

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