CAD tip # 1366:

Question

CAD

% platform category

How to generate a random number using AutoLISP?

Use the following function for a LISP generator of pseudo-random numbers:

(defun rnd (/ modulus multiplier increment random)
  (if (not seed)
    (setq seed (getvar "DATE"))
  )
  (setq modulus    65536
        multiplier 25173
        increment  13849
        seed  (rem (+ (* multiplier seed) increment) modulus)
        random     (/ seed modulus)
  )
)

Each call of the function (rnd) then returns a pseudo-random number in the range (0,1). E.g. to get random integers from 0 to 20, use (fix(* 20 (rnd))).

ACAD

*CAD

1.6.2001 20921×

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this tip shared by ARKANCE experts applies to: AutoCAD ·

See also:
Tip 14864:	How to generate a spirograph curve, guilloche, for CAD applications?
Tip 14861:	RegExpCnt - LISP string replace function with arithmetic/counter-extension
Tip 14851:	Shrinkwrap - boundary curve of DWG drawing polylines.
Tip 14832:	Convert polylines to alignments in Civil 3D.
Tip 14795:	How to transfer named layer states from another DWG drawing?

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