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))).

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* CAD

1.6.2001 18980×

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See also:
Tip 14085:	JavaScript API support in AutoCAD and AutoCAD LT.
Tip 14063:	How to get week day and week number from a given date.
Tip 14061:	Animated drawing of geometry in AutoCAD.
Tip 14056:	How to move blocks in the Z axis to the terrain model surface?
Tip 14048:	List of disks, CD-ROM drives, USBs and other disk functions for LISP.

Selected tip: Unknown VBA macros are inserted to my drawings.

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