randi

rand — Generates a controlled random number series with interpolation between each new number.

Description

Generates a controlled random number series with interpolation between each new number.

Syntax

ares randi xamp, xcps [, iseed] [, isize] [, ioffset]
kres randi 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. randi will produce straight-line interpolation between each new number and the next.

Examples

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

Example 713. Example of the randi opcode.

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 RT audio input is needed too
; For Non-realtime ouput leave only the line below:
; -o randi.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

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

instr 1	;same values every time

krnd randi 100, 10
     printk .5, krnd			; look 
aout oscili 0.8, 440+krnd, 1		; & listen
     outs aout, aout

endin

instr 2	;different values every time

krnd randi 100, 10, 10			; seed from system clock
     printk .5, 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:

 i   1 time     0.00067:    50.00000
 i   1 time     0.50000:   -75.81672
 i   1 time     1.00000:    95.93833

WARNING: Seeding from current time 1482746120

 i   2 time     2.00067:   -17.94434
 i   2 time     2.50000:   -14.11875
 i   2 time     3.00000:   -72.41545
      

See Also

rand, randh