rand
Prev | Orchestra Opcodes and Operators | Next

## rand

rand — Generates a controlled random number series.

## Description

Output is a controlled random number series between -amp and +amp

## Syntax

    ares rand xamp [, iseed] [, isel] [, ioffset]

    kres rand xamp [, iseed] [, isel] [, ioffset]

## Initialization

iseed (optional, default=0.5) -- a seed value for the recursive pseudo-random formula. A value between 0 and 1 will produce an initial output of kamp * iseed. A value greater than 1 will be seeded from the system clock. A negative value will cause seed re-initialization to be skipped. The default seed value is .5.

isel (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.

ares, kres -- Random number produced.

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 value ares or kres is within is a half-closed interval which contains -xamp, but never contains +xamp.

## Examples

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

Example 842. Example of the rand 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 rand.wav -W ;;; for file output any platform
    </CsOptions>
    <CsInstruments>

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

    instr 1	;same values every time

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

    endin

    instr 2	;different values every time

    krnd rand 100, 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:    50.00305
     i   1 time     0.50000:    62.71362
     i   1 time     1.00000:   -89.31885

    WARNING: Seeding from current time 472230558

     i   2 time     2.00067:   -70.65735
     i   2 time     2.50000:    69.15283
     i   2 time     3.00000:   -48.79761

## See Also

randh, randi

## Credits

Thanks to a note from John ffitch, I changed the names of the parameters.

Prev | Up | Next
r2c | Home | randh