GEN21 — Generates tables of different random distributions.
This generates tables of different random distributions. (See also betarand, bexprnd, cauchy, exprand, gauss, linrand, pcauchy, poisson, trirand, unirand, and weibull)
time and size are the usual GEN function arguments. level defines the amplitude. Note that GEN21 is not self-normalizing as are most other GEN functions. type defines the distribution to be used as follow:
1 = Uniform (positive numbers only)
2 = Linear (positive numbers only)
3 = Triangular (positive and negative numbers)
4 = Exponential (positive numbers only)
5 = Biexponential (positive and negative numbers)
6 = Gaussian (positive and negative numbers)
7 = Cauchy (positive and negative numbers)
8 = Positive Cauchy (positive numbers only)
9 = Beta (positive numbers only)
10 = Weibull (positive numbers only)
11 = Poisson (positive numbers only)
Of all these cases only 9 (Beta) and 10 (Weibull) need extra arguments. Beta needs two arguments and Weibull one.
If type = 6, the random numbers in the ftable follow a normal distribution centered around 0.0 (mu = 0.0) with a variance (sigma) of level / 3.83. Thus more than 99.99% of the random values generated are in the range -level to +level. The default value for level is 1 (sigma = 0.261). If a mean value different of 0.0 is desired, this mean value has to be added to the generated numbers.
f1 0 1024 21 1 ; Uniform (white noise) f1 0 1024 21 6 ; Gaussian (mu=0.0, sigma=1/3.83=0.261) f1 0 1024 21 6 5.745 ; Gaussian (mu=0.0, sigma=5.745/3.83=1.5) f1 0 1024 21 9 1 1 2 ; Beta (note that level precedes arguments) f1 0 1024 21 10 1 2 ; Weibull
All of the above additions were designed by the author between May and December 1994, under the supervision of Dr. Richard Boulanger.
Here is a complete example of the GEN21 routine. It uses the file gen21.csd.
Example 1202. Example of the GEN21 routine.
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 -odac ;;;realtime audio out ;-iadc ;;;uncomment -iadc if realtime audio input is needed too ; For Non-realtime ouput leave only the line below: ; -o gen21.wav -W ;;; for file output any platform </CsOptions> <CsInstruments> sr = 44100 ksmps = 32 nchnls = 2 0dbfs = 1 instr 1 ifn = p4 isize = ftlen(ifn) prints "TABLE NUMBER: %d\n", ifn prints "Index\tValue\n" iindex = 0 ;start loop begin_loop: ivalue tab_i iindex, ifn prints "%d:\t%f\n", iindex, ivalue iindex = iindex + 1 if (iindex < isize) igoto begin_loop ;produce sound - and repeat it 10 times so you can hear the patterns: aphase phasor 10/10 ;play all 32 values 10x over 10 seconds aphase = aphase*isize ;step through table afrq table aphase, p4 ;read table number asig poscil .5, (afrq*500)+1000,10 ;scale values of table 500 times, add 1000 Hz outs asig , asig ;so we can distinguish the different tables endin </CsInstruments> <CsScore> f1 0 32 21 1 ;Uniform (white noise) f2 0 32 21 6 ;Gaussian (mu=0.0, sigma=1/3.83=0.261) f3 0 32 21 6 5.745 ;Gaussian (mu=0.0, sigma=5.745/3.83=1.5) f4 0 32 21 9 1 1 2 ;Beta (note that level precedes arguments) f5 0 32 21 10 1 2 ;Weibull f10 0 8192 10 1 ;Sine wave i 1 0 10 1 i 1 11 10 2 i 1 22 10 3 i 1 33 10 4 i 1 44 10 5 e </CsScore> </CsoundSynthesizer>
These are the diagrams of the waveforms of the GEN21 routines, as used in the example: