Allow scalar expansion of input ports
Specifies that the input to your S-function input ports can have a width of either 1 or the size specified by the port, usually referred to as the block width. The S-function expands scalar inputs to the same dimensions as the block width. See Scalar Expansion of Inputs for more information.
See sfun_multiport.c,
the source file for the sfcndemo_sfun_multiport example,
for an example.