how to change the axis name with assembler expressions

This approach won't work as the expectation is that the function returns a number or a waveform; if you had done a sweep (and this had worked) then you could have ended up with lots of separate plots - also, the expression evaluation in the background would fail and it wouldn't know whether this is a waveform or a scalar.

The code below can be used to give you a calculator function that allows you to update the x and/or y axis names. Not sure that plotting the y axis name as "NF" (Noise Figure) makes sense when it's s22, but presumably it makes sense to you!

/* abSetAxisNames.il

Author     A.D.Beckett
Group      Custom IC (UK), Cadence Design Systems Ltd.
Language   SKILL
Date       Feb 15, 2026 
Modified   
By         

Set either the x-axis name, the y-axis name, or both for a signal.

abSetAxisNames(VT("/out") ?xname "something" ?yname "else")

Both keyword arguments are optional; if omitted, that axis name is
unchanged.

To use in the calculator (from IC617) use the fx button in the Function
Panel or the + button in the Expression Build to register the function.

***************************************************

SCCS Info: @(#) abSetAxisNames.il 02/15/26.10:30:02 1.1

*/

/***************************************************************
*                                                              *
*   (abSetAxisNames wave [?xname "new x"] [?yname "new y"])    *
*                                                              *
*    Update the x-axis name (label) and/or the y-axis name.    *
*                                                              *
***************************************************************/

(defun abSetAxisNames (wave @key xname yname)
  (when (symbolp xname)
    (setq xname (symbolToString xname)))
  (when (symbolp yname)
    (setq yname (symbolToString yname)))
  (cond 
    ((drIsWaveform wave)
     (when xname
       (putpropq (drGetWaveformXVec wave) xname name))
     (when yname
       (putpropq (drGetWaveformYVec wave) yname name))
     wave
     )
    ((famIsFamily wave)
     (famMap 'abSetAxisNames wave ?xname xname ?yname yname)
     )
    (t wave)
    )
  )

;
;;;;;;;;;;;;;;;;;;;;;;;;;; GUI builder information ;;;;;;;;;;;;;;;;;;;;;;;;;;;
ocnmRegGUIBuilder(
 '(nil
  function abSetAxisNames
  name abSetAxisNames
  description "abSetAxisNames"
  category ("Custom Functions")
  analysis (nil
      general (nil
        args (wave xname yname )
          signals (nil
                wave (nil
                      prompt "wave"
                      tooltip "wave"
                      )
           )
          params(nil
                 xname (nil
                       prompt "X Name"
                       tooltip "X Axis Name"
                       guiRowHint 1
                       type string
                       required nil
                       keyed t
                 )
                 yname (nil
                       prompt "Y Name"
                       tooltip "Y Axis Name"
                       guiRowHint 1
                       type string
                       required nil
                       keyed t
                 )
          )
        inputrange t
      )
  )
  outputs(result)
 )
)

This approach won't work as the expectation is that the function returns a number or a waveform; if you had done a sweep (and this had worked) then you could have ended up with lots of separate plots - also, the expression evaluation in the background would fail and it wouldn't know whether this is a waveform or a scalar.

The code below can be used to give you a calculator function that allows you to update the x and/or y axis names. Not sure that plotting the y axis name as "NF" (Noise Figure) makes sense when it's s22, but presumably it makes sense to you!

/* abSetAxisNames.il

Author     A.D.Beckett
Group      Custom IC (UK), Cadence Design Systems Ltd.
Language   SKILL
Date       Feb 15, 2026 
Modified   
By         

Set either the x-axis name, the y-axis name, or both for a signal.

abSetAxisNames(VT("/out") ?xname "something" ?yname "else")

Both keyword arguments are optional; if omitted, that axis name is
unchanged.

To use in the calculator (from IC617) use the fx button in the Function
Panel or the + button in the Expression Build to register the function.

***************************************************

SCCS Info: @(#) abSetAxisNames.il 02/15/26.10:30:02 1.1

*/

/***************************************************************
*                                                              *
*   (abSetAxisNames wave [?xname "new x"] [?yname "new y"])    *
*                                                              *
*    Update the x-axis name (label) and/or the y-axis name.    *
*                                                              *
***************************************************************/

(defun abSetAxisNames (wave @key xname yname)
  (when (symbolp xname)
    (setq xname (symbolToString xname)))
  (when (symbolp yname)
    (setq yname (symbolToString yname)))
  (cond 
    ((drIsWaveform wave)
     (when xname
       (putpropq (drGetWaveformXVec wave) xname name))
     (when yname
       (putpropq (drGetWaveformYVec wave) yname name))
     wave
     )
    ((famIsFamily wave)
     (famMap 'abSetAxisNames wave ?xname xname ?yname yname)
     )
    (t wave)
    )
  )

;
;;;;;;;;;;;;;;;;;;;;;;;;;; GUI builder information ;;;;;;;;;;;;;;;;;;;;;;;;;;;
ocnmRegGUIBuilder(
 '(nil
  function abSetAxisNames
  name abSetAxisNames
  description "abSetAxisNames"
  category ("Custom Functions")
  analysis (nil
      general (nil
        args (wave xname yname )
          signals (nil
                wave (nil
                      prompt "wave"
                      tooltip "wave"
                      )
           )
          params(nil
                 xname (nil
                       prompt "X Name"
                       tooltip "X Axis Name"
                       guiRowHint 1
                       type string
                       required nil
                       keyed t
                 )
                 yname (nil
                       prompt "Y Name"
                       tooltip "Y Axis Name"
                       guiRowHint 1
                       type string
                       required nil
                       keyed t
                 )
          )
        inputrange t
      )
  )
  outputs(result)
 )
)