Beta distribution random number generator (positive values only). This is an x-class noise generator.
ar betarand krange, kalpha, kbeta
ir betarand krange, kalpha, kbeta
kr betarand krange, kalpha, kbeta
krange -- range of the random numbers (0 - krange).
kalpha -- alpha value. If kalpha is smaller than one, smaller values favor values near 0.
kbeta -- beta value. If kbeta is smaller than one, smaller values favor values near krange.
If both kalpha and kbeta equal one we have uniform distribution. If both kalpha and kbeta are greater than one we have a sort of Gaussian distribution. Outputs only positive numbers.
For more detailed explanation of these distributions, see:
C. Dodge - T.A. Jerse 1985. Computer music. Schirmer books. pp.265 - 286
D. Lorrain. A panoply of stochastic cannons. In C. Roads, ed. 1989. Music machine . Cambridge, Massachusetts: MIT press, pp. 351 - 379.
Here is an example of the betarand opcode. It uses the files betarand.orc and betarand.sco.
Example 1. Example of the betarand opcode.
/* betarand.orc */
; Initialize the global variables.
sr = 44100
kr = 4410
ksmps = 10
nchnls = 1
; Instrument #1.
instr 1
; Generate a number between 0 and 1 with a
; uniform distribution.
; krange = 1
; kalpha = 1
; kbeta = 1
i1 betarand 1, 1, 1
print i1
endin
/* betarand.orc */
/* betarand.sco */
; Play Instrument #1 for one second.
i 1 0 1
e
/* betarand.sco */
instr 1: i1 = 24583.412