urandom

urandom — truly random opcodes with controllable range.

Description

Plugin opcode in urandom.

Truly random opcodes with controllable range. These units are for Unix-like systems only and use /dev/urandom to construct Csound random values

Syntax

ax urandom [imin, imax]
ix urandom [imin, imax]
kx urandom [imin, imax]

Initialization

ix -- i-rate output value.

imin -- minimum value of range; defaults to -1.

imax -- maximum value of range; defaults to +1.

[Note] Notes

The algorithm produces 2^64 different possible values which are scaled to fit the range requested. The randomness comes form the usual Linux/OSX /dev/urandom method, and there is no guarantee that it will be truly random, but there is a good chance. It does not show any cycles.

Performance

ax -- a-rate output value.

kx -- k-rate output value.

Examples

Here is an example of the urandom opcode at a-rate. It uses the file urandom.csd.

Example 1165. An example of the urandom opcode at a-rate.

See the sections Real-time Audio and Command Line Flags for more information on using command line flags.

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
; Audio out   Audio in
-odac      ;;;RT audio out
; For Non-realtime ouput leave only the line below:
; -o urandom.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

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

instr 1     ; Create random numbers at a-rate in the range -2 to 2
  
aur     urandom  -2, 2
afreq1  =   aur * 500 + 100         ; Use the random numbers to choose a frequency.
afreq2  =   aur * 500 + 200
a1 oscil .3, afreq1
a2 oscil .3, afreq2
outs a1, a2
endin

</CsInstruments>
<CsScore>
i 1 0 3
e
</CsScore>
</CsoundSynthesizer>


Here is an example of the urandom opcode at k-rate. It uses the file urandom_krate.csd.

Example 1166. An example of the urandom opcode at k-rate.

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
; Audio out   Audio in
-odac      ;;;RT audio out
; For Non-realtime ouput leave only the line below:
; -o urandom_krate.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

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

instr 1 ; Create random numbers at k-rate in the range -1 to 1 at krate
   
k1 urandom                              ; with a uniform distribution.
printks "k1=%f\\n", 0.1, k1
asig1    poscil.2, k1 * 500 + 100
asig2    poscil.2, k1 * 500 + 200
outs    asig1, asig2    
endin

</CsInstruments>
<CsScore>
i 1 0 3
e
</CsScore>
</CsoundSynthesizer>


Its output should include lines like this:

k1=0.229850
k1=-0.077047
k1=-0.199339
k1=-0.620577
k1=-0.119447
k1=-0.596258
k1=0.525800
k1=-0.171583
k1=-0.017196
k1=-0.974613
k1=-0.036276
      

See also

Random (Noise) Generators

Credits

Author: John ffitch

New in version 5.13