Description

Generates random numbers and holds them for a period of time.

Syntax

ares randh xamp, xcps [, iseed] [, isize] [, ioffset]

kres randh kamp, kcps [, 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 negative value will cause seed re-initialization to be skipped. A value greater than 1 will seed from system time, this is the best option to generate a different random sequence for each run.

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. randh will hold each new number for the period of the specified cycle.

Examples

Here is an example of the randh opcode. It uses the file randh.csd.

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
-odac     ;;;realtime audio out
;-iadc    ;;;uncomment -iadc if RT audio input is needed too
; For Non-realtime ouput leave only the line below:
; -o randh.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

sr = 44100
ksmps = 32
nchnls = 2
0dbfs  = 1

instr 1	;same values every time

krnd randh 100, 10
     printk2 krnd			; look 
aout oscili 0.8, 440+krnd, 1		; & listen
     outs aout, aout

endin

instr 2	;different values every time

krnd randh 100, 10, 10			; seed from system clock
     printk2 krnd			; look 
aout oscili 0.8, 440+krnd, 1		; & listen
     outs aout, aout

endin
</CsInstruments>
<CsScore>
f 1 0 16384 10 1	;sine wave.

i 1 0 1
i 2 2 1
e
</CsScore>
</CsoundSynthesizer>

The example will produce the following output:

 i1    50.00000
 i1    50.00305
 i1    97.68677
 i1   -44.25354
 i1   -61.56006
 i1   -75.91248
 i1    67.57202
 i1    12.83875
 i1     5.39551
 i1   -95.18738

WARNING: Seeding from current time 684387922

 i2   -13.81226
 i2   -16.49475
 i2    69.51904
 i2    35.04944
 i2    47.47925
 i2    63.25378
 i2   -59.61914
 i2    50.93079
 i2    -6.46362
 i2     5.89294
      

See also

Random (Noise) Generators rand, randi