How to creat a uniform distribution in source file for Monte-Carlo simulation?

Laurent,

You were asking about $rdist_uniform so I assumed you wanted a uniform distribution, not a gaussian (normal) distribution. You can use this SKILL code below if you want to generate random numbers with a gaussian distribution:

/* abRandomNormal.il

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

Uses Box-Muller method to produce random numbers with
a normal distribution (mean 0, std dev 1).

Call abRandomNormal() multiple times to get such a sequence.

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

SCCS Info: @(#) abRandomNormal.il 11/30/12.14:22:28 1.1

*/

;------------------------------------------------------------------------
; Store math constants (such as PI) as properties on this symbol
;------------------------------------------------------------------------
(defMathConstants 'abRandomNormal)

/***************************************************************
*                                                              *
*                       (abRandomNormal)                       *
*                                                              *
*  Return a random number with normal distribution using the   *
*                      Box-Muller method                       *
*                                                              *
***************************************************************/
(defun abRandomNormal ()
  (let ((max (rightshift -1 1)) U V)
    (setq U (quotient (float (random max)) max))
    (setq V (quotient (float (random max)) max))
    ;--------------------------------------------------------------------
    ; could generate two independent numbers
    ; the other would use cos instead of sin
    ;--------------------------------------------------------------------
    (times (sqrt (times -2 (log U))) 
           (cos (times 2 (getqq abRandomNormal PI) V)))
    )
  )

/***************************************************************
*                                                              *
*             (abTestRandomNormal numPoints bins)              *
*                                                              *
*   Function for testing - uses ViVA's plotting functions to   *
*  produce a histogram and also compute the mean and std dev   *
*      to ensure that with enough points it looks normal       *
*               (e.g numPoints 100000, bins 100)               *
*                                                              *
***************************************************************/

(defun abTestRandomNormal (numPoints bins)
  (let (x y wave)
    (setq x (drCreateVec 'intlong numPoints))
    (setq y (drCreateVec 'double numPoints))
    (for i 0 numPoints
         (drAddElem x i)
         (drAddElem y (abRandomNormal))
         )
    (setq wave (drCreateWaveform x y))
    (awvPlotWaveform (newWindow) (list (histo wave bins nil nil)))
    (printf "Mean=%g\nStd Dev=%g\n" (average wave) (stddev wave))
    )
  )

Regards,

Andrew.

Laurent,

You were asking about $rdist_uniform so I assumed you wanted a uniform distribution, not a gaussian (normal) distribution. You can use this SKILL code below if you want to generate random numbers with a gaussian distribution:

/* abRandomNormal.il

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

Uses Box-Muller method to produce random numbers with
a normal distribution (mean 0, std dev 1).

Call abRandomNormal() multiple times to get such a sequence.

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

SCCS Info: @(#) abRandomNormal.il 11/30/12.14:22:28 1.1

*/

;------------------------------------------------------------------------
; Store math constants (such as PI) as properties on this symbol
;------------------------------------------------------------------------
(defMathConstants 'abRandomNormal)

/***************************************************************
*                                                              *
*                       (abRandomNormal)                       *
*                                                              *
*  Return a random number with normal distribution using the   *
*                      Box-Muller method                       *
*                                                              *
***************************************************************/
(defun abRandomNormal ()
  (let ((max (rightshift -1 1)) U V)
    (setq U (quotient (float (random max)) max))
    (setq V (quotient (float (random max)) max))
    ;--------------------------------------------------------------------
    ; could generate two independent numbers
    ; the other would use cos instead of sin
    ;--------------------------------------------------------------------
    (times (sqrt (times -2 (log U))) 
           (cos (times 2 (getqq abRandomNormal PI) V)))
    )
  )

/***************************************************************
*                                                              *
*             (abTestRandomNormal numPoints bins)              *
*                                                              *
*   Function for testing - uses ViVA's plotting functions to   *
*  produce a histogram and also compute the mean and std dev   *
*      to ensure that with enough points it looks normal       *
*               (e.g numPoints 100000, bins 100)               *
*                                                              *
***************************************************************/

(defun abTestRandomNormal (numPoints bins)
  (let (x y wave)
    (setq x (drCreateVec 'intlong numPoints))
    (setq y (drCreateVec 'double numPoints))
    (for i 0 numPoints
         (drAddElem x i)
         (drAddElem y (abRandomNormal))
         )
    (setq wave (drCreateWaveform x y))
    (awvPlotWaveform (newWindow) (list (histo wave bins nil nil)))
    (printf "Mean=%g\nStd Dev=%g\n" (average wave) (stddev wave))
    )
  )

Regards,

Andrew.