rand

rand --  Generates a controlled random number series.

Description

Output is a controlled random number series between -amp and +amp

Syntax

ar rand xamp [, iseed] [, isize] [, ioffset]

kr rand xamp [, iseed] [, isize] [, ioffset]

Initialization

iseed (optional, default=0.5) -- seed value for the recursive pseudo-random formula. A value between 0 and +1 will produce an initial output of kamp * iseed. A value greater than 1 will be used directly, without scaling. A negative value will cause seed re-initialization to be skipped. The default seed value is .5.

isize (optional, default=0) -- if zero, a 16 bit number is generated. If non-zero, a 31-bit random number is generated. Default is 0.

ioffset (optional, default=0) -- a base value added to the random result. New in Csound version 4.03.

Performance

kamp, xamp -- range over which random numbers are distributed.

kcps, xcps -- the frequency which new random numbers are generated.

The internal pseudo-random formula produces values which are uniformly distributed over the range kamp to -kamp. rand will thus generate uniform white noise with an R.M.S value of kamp / root 2.

The remaining units produce band-limited noise: the kcps and xcps parameters permit the user to specify that new random numbers are to be generated at a rate less than the sampling or control frequencies.

Examples

Here is an example of the rand opcode. It uses the files rand.orc and rand.sco.

Example 1. Example of the rand opcode.

/* rand.orc */
/* Written by Kevin Conder */
; Initialize the global variables.
sr = 44100
kr = 4410
ksmps = 10
nchnls = 1

; Instrument #1.
instr 1
  ; Choose a random frequency between 4,100 and 44,100.
  kfreq rand 40000
  kcps = kfreq + 4100

  a1 oscil 30000, kcps, 1
  out a1
endin
/* rand.orc */
        
/* rand.sco */
/* Written by Kevin Conder */
; Table #1, a sine wave.
f 1 0 16384 10 1

; Play Instrument #1 for one second.
i 1 0 1
e
/* rand.sco */
        

See Also

randh, randi