zamod
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## zamod

zamod — Modulates one a-rate signal by a second one.

## Description

Modulates one a-rate signal by a second one.

## Syntax

    ares zamod asig, kzamod

## Performance

asig -- the input signal

kzamod -- controls which za variable is used for modulation. A positive value means additive modulation, a negative value means multiplicative modulation. A value of 0 means no change to asig.

zamod modulates one a-rate signal by a second one, which comes from a za variable. The location of the modulating variable is controlled by the i-rate or k-rate variable kzamod. This is the a-rate version of zkmod.

## Examples

Here is an example of the zamod opcode. It uses the files zamod.orc and zamod.sco.

Example 441. Example of the zamod opcode.

    /* zamod.orc */
    ; Initialize the global variables.
    sr = 44100
    kr = 4410
    ksmps = 10
    nchnls = 1

    ; Initialize the ZAK space.
    ; Create 2 a-rate variables and 2 k-rate variables.
    zakinit 2, 2

    ; Instrument #1 -- a simple waveform.
    instr 1
      ; Vary an a-rate signal linearly from 20,000 to 0.
      asig line 20000, p3, 0

      ; Send the signal to za variable #1.
      zaw asig, 1
    endin

    ; Instrument #2 -- generates audio output.
    instr 2
      ; Generate a simple sine wave.
      asin oscil 1, 440, 1

      ; Modify the sine wave, multiply its amplitude by
      ; za variable #1.
      a1 zamod asin, -1

      ; Generate the audio output.
      out a1

      ; Clear the za variables, prepare them for
      ; another pass.
      zacl 0, 2
    endin
    /* zamod.orc */

    /* zamod.sco */
    ; Table #1, a sine wave.
    f 1 0 16384 10 1

    ; Play Instrument #1 for 2 seconds.
    i 1 0 2
    ; Play Instrument #2 for 2 seconds.
    i 2 0 2
    e
    /* zamod.sco */

## See Also

zacl, ziw, ziwm

## Credits

Author: Robin Whittle
Australia
May 1997

Example written by Kevin Conder.

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