straight line (best) fit using viva calculator

Hi Andrew,

I try to include this abBestFit.il to calculator. But I dont know why after adding the function, 5 different sub-functions are added

-abBestFitCoeffs

-computeCoeffs

-mean

-sampleCorrCoeff

-uncorrectedStdde

but not abBestFit. Do you know what is the reason? My cds vesion is IC618-64b 500.2

BR

First of all, the code must have a .ils suffix, not .il because it relies on SKILL++ lexical scoping. I'm not sure whether you kept that (you referred to it as abBestFit.il). Secondly, I updated the code in the post above to a newer version that has the calculator registration functions included, so it should be straightforward to add, especially as you're adding it in a version that supports adding .ils files in the calculator (see the comments at the top of the new code).

Andrew.

hi Andrew, it works, thanks for your help!

Hello Andrew,

Is there a function that can be used to construct a line between two chosen points (not first and last points) in waveform? Or can this abFirstLastLine function choose the points to construct a line?

Thanks,

Hannah

Hi Hannah,

No, but it wouldn't be that hard to write one. Perhaps you can expand upon what you want though by answering these questions?

1. How would you specify the two points that you want to construct the line to go through? Maybe by specifying two x values and then the function determines the y values at those points to decide the line?
2. Would the line be extrapolated to the first x and last x value in the source waveform? (so in other words, it would have the same x-range as the source waveform, but would go through the points specified by two specific x values)

That seems the most logical way to do it to me.

Andrew 

Hello Andrew,

Thank you for replying to me.

1.The endpoints fit line function (abFirstLastLine) chooses the first and last points of the input waveform. I am finding a way to draw a fit line of the source waveform with two endpoints different from the first and last points of the source waveform. This means I can choose two x values as the input of the function and set these two corresponding points as the endpoints of the line. 

2. Yes, the line would have the same x-range as the source waveform, but would go through the points specified by two specific x values.

Appreciate your help!

Hannah,

Try this. You can use the "fx" button in the function panel of the calculator, or the + button in the ADE Explorer/Assembler expression builder to add to the calculator.

Regards,

Andrew

/* abLineThroughTwoPoints.il

Author     A.D.Beckett
Group      Custom IC (UK), Cadence Design Systems Ltd.
Language   SKILL
Date       Mar 23, 2021 
Modified   
By         

Construct a line which passes through the y values at two specified
x points on an input waveform, and has the same x-range as the
input waveform.

Includes function template so this can be added to the calculator
with the "fx" button in the calculator function panel.

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

SCCS Info: @(#) abLineThroughTwoPoints.il 03/23/21.20:07:57 1.1

*/

/***************************************************************
*                                                              *
*             (abLineThroughTwoPoints wave x1 x2)              *
*                                                              *
*  Produce a waveform which intersects the original waveform   *
* at two specified x values. The x-range of the result is the  *
*                same as the original waveform.                *
*                                                              *
***************************************************************/

(defun abLineThroughTwoPoints (wave x1 x2)
  (cond
    ((drIsWaveform wave)
     (let (xVec yVec newXVec newYVec len newWave y1 y2 m c)
       ;-----------------------------------------------------------------
       ; Calculate slope and intercept from two points
       ;-----------------------------------------------------------------
       (setq y1 (value wave x1))
       (setq y2 (value wave x2))
       (if (equal x1 x2)
         (progn
           (setq m 0.0)
           (setq c y1))
         (progn
           (setq m (quotient (difference y2 y1) (difference x2 x1)))
           (setq c (difference y2 (times m x2)))
           ))
       (setq xVec (drGetWaveformXVec wave))
       (setq yVec (drGetWaveformYVec wave))
       (setq len (drVectorLength xVec))
       (setq newXVec (drCreateVec 'double 2))
       (setq newYVec (drCreateVec 'double 2))
       (drAddElem newXVec (drGetElem xVec 0))
       (drAddElem newXVec (drGetElem xVec (sub1 len)))
       (drAddElem newYVec (plus (times (drGetElem xVec 0) m) c))
       (drAddElem newYVec (plus (times (drGetElem xVec (sub1 len)) m) c))
       ;-----------------------------------------------------------------
       ; Sort out attributes for new waveform to match input
       ;-----------------------------------------------------------------
       (putpropq newXVec (getq xVec units) units)
       (putpropq newXVec (getq xVec name) name)
       (putpropq newYVec (getq yVec units) units)
       (putpropq newYVec (getq yVec name) name)
       (setq newWave (drCreateWaveform newXVec newYVec))
       (famSetExpr newWave `(abLineThroughTwoPoints ,(famGetExpr wave)))
       newWave
       )
     )
    ((famIsFamily wave)
     (famMap 'abLineThroughTwoPoints wave x1 x2)
     )
    (t
      (error "abLineThroughTwoPoints: cannot handle %L\n" wave)
      )
    )
  )

;
;;;;;;;;;;;;;;;;;;;;;;;;;; GUI builder information ;;;;;;;;;;;;;;;;;;;;;;;;;;;
ocnmRegGUIBuilder(
 '(nil
  function abLineThroughTwoPoints
  name abLineThroughTwoPoints
  description "Generate line which intersects curve at two x values"
  category ("Custom Functions")
  analysis (nil
      general (nil
        args (wave x1 x2 )
          signals (nil
                wave (nil
                      prompt "Waveform"
                      tooltip "Waveform"
                      )
           )
          params(nil
                 x1 (nil
                       prompt "X1"
                       tooltip "X1"
                       guiRowHint 1
                       type float
                       required t
                 )
                 x2 (nil
                       prompt "X2"
                       tooltip "X2"
                       guiRowHint 1
                       type float
                       required t
                 )
          )
        inputrange t
      )
  )
  outputs(result)
 )
)

Hello Andrew,

I tried this function and it works! Thank you so much for your help!