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cuserrnd

Continuous USER-defined-distribution RaNDom generator.

Syntax

aout cuserrnd kmin, kmax, ktableNum
iout cuserrnd imin, imax, itableNum
kout cuserrnd kmin, kmax, ktableNum

Initialization

imin -- minimum range limit

imax -- maximum range limit

itableNum -- number of table containing the random-distribution function. Such table is generated by the user. See GEN40, GEN41, and GEN42. The table length does not need to be a power of 2.

Performance

ktableNum -- number of table containing the random-distribution function. Such table is generated by the user. See GEN40, GEN41, and GEN42. The table length does not need to be a power of 2.

kmin -- minimum range limit

kmax -- maximum range limit

cuserrnd (continuous user-defined-distribution random generator) generates random values according to a continuous random distribution created by the user. In this case the shape of the distribution histogram can be drawn or generated by any GEN routine. The table containing the shape of such histogram must then be translated to a distribution function by means of GEN40 (see GEN40 for more details). Then such function must be assigned to the XtableNum argument of cuserrnd. The output range can then be rescaled according to the Xmin and Xmax arguments. cuserrnd linearly interpolates between table elements, so it is not recommended for discrete distributions (GEN41 and GEN42).

For a tutorial about random distribution histograms and functions see:

  • D. Lorrain. "A panoply of stochastic cannons". In C. Roads, ed. 1989. Music machine. Cambridge, Massachusetts: MIT press, pp. 351 - 379.

Examples

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

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

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

instr 1 ; every run time same values

kuser cuserrnd 0, 100, 1
      printk .2, kuser
asig  poscil .5, 220+kuser, 3
      outs asig, asig
endin

instr 2 ; every run time different values

      seed 0
kuser cuserrnd 0, 100, 1
      printk .2, kuser
asig  poscil .5, 220+kuser, 3
      outs asig, asig
endin
</CsInstruments>
<CsScore>
f 1 0 16 -7 1 4 0 8 0 4 1       ;distrubution using GEN07
f 2 0 16384 40 1                ;GEN40 is to be used with cuserrnd
f 3 0 8192 10 1                 ;sine

i 1 0 2
i 2 3 2
e
</CsScore>
</CsoundSynthesizer>

Its output should include lines like these:

i   1 time     0.00067:    53.14918
i   1 time     0.20067:     0.00000
i   1 time     0.40067:     0.00000
i   1 time     0.60067:    96.80406
i   1 time     0.80067:    94.20729
i   1 time     1.00000:     0.00000
i   1 time     1.20067:    86.13032
i   1 time     1.40067:    31.37096
i   1 time     1.60067:    70.35889
i   1 time     1.80000:     0.00000
i   1 time     2.00000:    49.18914

WARNING: Seeding from current time 2006647442

i   2 time     3.00067:    21.45002
i   2 time     3.20067:    44.32333
i   2 time     3.40067:    46.05420
i   2 time     3.60000:     0.00000
i   2 time     3.80067:    41.32175
i   2 time     4.00000:     0.00000
i   2 time     4.20000:    63.72019
i   2 time     4.40067:     0.00000
i   2 time     4.60067:     0.00000
i   2 time     4.80067:     0.00000
i   2 time     5.00000:    74.49330

See also

Random (Noise) Generators

Credits

Author: Gabriel Maldonado

New in Version 4.16