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User-Defined Functions
The S-Function block provides access to S-functions from a block diagram. The S-function named as the S-function name parameter can be a Level-1 M-file or a Level-1 or Level-2 C MEX-file S-function (see Overview of S-Functions in Writing S-Functions for information on how to create S-functions).
The S-Function block allows additional parameters to be passed directly to the named S-function. The function parameters can be specified as MATLAB expressions or as variables separated by commas. For example,
A, B, C, D, [eye(2,2);zeros(2,2)]
Note that although individual parameters can be enclosed in brackets, the list of parameters must not be enclosed in brackets.
The S-Function block displays the name of the specified S-function and the number of input and output ports specified by the S-function. Signals connected to the inputs must have the dimensions specified by the S-function for the inputs.
Depends on the implementation of the S-Function block.

The S-function name.
Additional S-function parameters. See the preceding block description for information on how to specify the parameters.
This parameter applies only if this block represents a C MEX-file S-function and you intend to use the Real-Time Workshop software to generate code from the model containing the block. See Specifying Additional Source Files for an S-Function in the Real-Time Workshop online documentation for information on using this parameter.
Direct Feedthrough | Depends on contents of S-function |
Sample Time | Depends on contents of S-function |
Scalar Expansion | Depends on contents of S-function |
Dimensionalized | Depends on contents of S-function |
Multidimensionalized | Yes |
Zero Crossing | No |
![]() | Selector | S-Function Builder | ![]() |

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