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randi

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 of the randi opcode.
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<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

Random (Noise) Generators, randh, rand