The **RND** function returns a random number with a value between 0 (inclusive) and 1 (exclusive). ## Syntax > result! = [RND](RND) [(*n*)] ## Parameter(s) * *n* is a [SINGLE](SINGLE) numeric value that defines the behavior of the RND function but is **NOT normally required**: - n parameter omitted: Returns next random number in the sequence. - n = 0: Return the last value returned. - n < 0: Always returns the same value for any given n - n > 0: the sequence of numbers generated will not change unless [RANDOMIZE](RANDOMIZE) is initiated. ## Description * The random numbers generated range from 0 minimum to .9999999 maximum [SINGLE](SINGLE) values that never equal 1. * To get values in a range larger than 1, multiply RND with a number to get returns up to but not including that numerical value. * To get values starting at a certain number, add that number to the RND result as RND minimums can be 0. * If you need an integer range of numbers, like a dice roll, round it down to an [INT](INT). Add 1 to the maximum number with [INT](INT). * The random sequence is 2 ^ 24 or 16,777,216 entries long, which can allow repeated patterns in some procedures. * Formulas for the [INT](INT) or [CINT](CINT) of ANY number range from *min%*(lowest value) to *max%*(greatest value): * Using [INT](INT): randNum% = INT(RND * (max% - min% + 1)) + min% * Using [CINT](CINT): randNum% = CINT(RND * (max% - min%)) + min% * Use [RANDOMIZE](RANDOMIZE) [TIMER](TIMER) for different random number results each time a program is run. * [RUN](RUN) should reset the [RANDOMIZE](RANDOMIZE) sequence to the starting [RND](RND) function value.(Not yet in QB64) ## Example(s) Generating a random integer value between 1 and 6 (inclusive) using INT. ```vb dice% = INT(RND * 6) + 1 'add one as INT value never reaches 6 ``` Using uniform random numbers to create random numbers with a gaussian distribution ([http://en.wikipedia.org/wiki/Marsaglia_polar_method| Marsaglia's polar method]). ```vb DO u! = RND * 2 - 1 v! = RND * 2 - 1 s! = u! * u! + v! * v! LOOP WHILE s! >= 1 OR s! = 0 s! = SQR(-2 * LOG(s!) / s!) * 0.5 u! = u! * s! v! = v! * s! ``` > *Explanation:* Values *u!* and *v!* are now two independent random numbers with gaussian distribution, centered at 0. Random flashes from an explosion ```vb SCREEN _NEWIMAGE(640, 480, 32) RANDOMIZE TIMER BC = 120 ' BALL COUNT DIM ballx(1 TO BC) DIM bally(1 TO BC) DIM velx(1 TO BC) DIM vely(1 TO BC) DIM bsize(1 TO BC) Y = INT(RND * (400 - 100 + 1)) + 100 X0 = 325 Y0 = 300 Tmax = 150 DO FOR p = 1 TO BC T = INT(RND * (Tmax - 50 + 1)) + 50 X = INT(RND * (1000 + 500 + 1)) - 500 velx(p) = (X - X0) / T ' calculate velocity based on flight time vely(p) = -1 * (Y - .05 * (T ^ 2 + 20 * Y0)) / (T) ' verticle velocity NEXT p FOR w = 1 TO BC bsize(w) = INT(RND * (10 - 0 + 1)) + 0 'size NEXT w FOR J = 1 TO Tmax _LIMIT 60 CLS 'FOR i = 0 TO 255 STEP .5 'CIRCLE (X0, Y0), i, _RGB(255 - i, 0, 0), 0, 3.147 ' NEXT i R = INT(RND * (25 - 20 + 1)) + 20 'random glimmer FOR z = 1 TO BC ballx(z) = X0 + velx(z) * J bally(z) = Y0 - vely(z) * J + .5 * .1 * J ^ 2 NEXT z FOR d = 1 TO BC RCOL = INT(RND * (255 - 0 + 1)) 'color FOR i = 0 TO bsize(d) + 1 STEP .4 'draw balls CIRCLE (ballx(d), bally(d)), i, _RGBA(255, RCOL - (R * i), RCOL - R * i, 255) NEXT i NEXT d _DISPLAY NEXT J LOOP UNTIL INKEY$ <> "" ``` ## See Also * [RANDOMIZE](RANDOMIZE), [TIMER](TIMER) * [INT](INT), [CINT](CINT), [FIX](FIX)