Refers to an input or output port index, starting at 0. For example, the first input port of an S-function is 0.

User control variable. This is an advanced feature that overrides the lcv and sigIdx parameters. When used within an inlined S-function, it should generally be specified as "".

Loop control variable. This is generally generated by the %roll directive via the second %roll argument (e.g., lcv=RollThreshold) and should be passed directly to the library function. It contains either "", indicating that the current pass through the %roll is being inlined, or it is the name of a loop control variable such as "i", indicating that the current pass through the %roll is being placed in a loop. Outside the %roll directive, this is usually specified as "".

Signal index. Sometimes referred to as the signal element index. When accessing specific elements of an input or output signal directly, the call to the various library routines should have ucv="", lcv="", and sigIdx equal to the desired integer signal index starting at 0. For complex signals, sigIdx can be an overloaded integer index specifying both whether the real or imaginary part is being accessed and which element. When you access these items inside a %roll, use the sigIdx generated by the %roll directive.

Most functions that take a sigIdx argument accept it in an overloaded form, where sigIdx can be

• An integer, e.g., 3. If the referenced signal is complex, then this refers to the identifier for the complex container. If the referenced signal is not complex, then this refers to the identifier.

• An id-num, usually of the form (see Overloading sigIdx)

  1. "%<tRealPart>%<idx>" (e.g., "re3"). The real part of the signal element. Usually "%<tRealPart>%<sigIdx>" when sigIdx is generated by the %roll directive.

  2. "%<tImagPart>%<idx>" (e.g., "im3"). The imaginary part of the signal element or "" if the signal is not complex. Usually "%<tImagPart>%<sigIdx>" when sigIdx is generated by the %roll directive.

Use the idx name when referring to a state or work vector.

Functions that accept the three arguments ucv, lcv, sigIdx (or idx) are called differently depending upon whether or not they are used within a %roll directive. If they are used within a %roll directive, ucv is generally specified as "" and lcv and sigIdx are the same as those specified in the %roll directive. If they are not used within a %roll directive, ucv and lcv are generally specified as "", and sigIdx specifies the index to access.

Parameter index. Sometimes referred to as the parameter element index. The handling of this parameter is very similar to sigIdx above: it can be #, re#, or im#.

State index. Sometimes referred to as the state vector element index. It must evaluate to an integer where the first element starts at 0.

Yes

Real part of element 3

u0[2].re

real_T

Yes

Imaginary part of element 3

u0[2].im

real_T

Yes

Complex container of element 3

u0[2]

creal_T

Yes

Complex container of element 3

u0[2]

creal_T

No

Element 3

u0[2]

real_T

No

""

N/A

N/A

No

Element 3

u0[2]

real_T

No

Element 3

u0[2]

real_T

Yes

Real part of element i

Yes

Imaginary part of element ii

Yes

Complex container of element i

Yes

Complex container of element i

No

Element i

No

""

No

Element i

No

Element i